12 Best Smartwatches for Blood Oxygen Tracking (October 2026) Honest Reviews

The Garmin vivoactive 4 is the best smartwatch for blood oxygen tracking in 2026 because it combines a continuous Pulse Ox sensor with a battery that lasts up to eight days, so the overnight data you actually want keeps collecting while you sleep. The Apple Watch Series 11 takes the crown for health-feature depth, and the Amazfit Bip 6 delivers 24/7 SpO2 with a 14-day battery at a budget price point.

That combination matters more than most buyers expect. A watch can list blood oxygen on the box and still be nearly useless for the reason you bought it: some only sample a few times a day, some need you to raise your wrist and hold still, and some kill the battery if you leave the sensor running overnight. The sampling mode is the single most overlooked spec in this whole category.

SpO2 is the percentage of your haemoglobin carrying oxygen, and a healthy adult at sea level usually sits between 95 and 100 percent. Watches estimate it with red and infrared light using photoplethysmography, the same principle as a fingertip clip oximeter but measured indirectly through skin and bone. One caveat up front: none of these watches is a diagnostic device, and the ECG and AFib features on some models are cleared while the SpO2 feature usually is not. For a suspected heart or lung problem, use a medical oximeter and see a clinician.

We spent several weeks wearing all twelve of these watches against the same routine, checking overnight sampling, spot-check consistency, fit and comfort, and how the data holds up when you move. Our broader picks for sleep tracking and fitness tracking cover the wider smartwatch category, but this roundup is narrow on purpose.

The Three Best Watches for Blood Oxygen Tracking in 2026

These are the three picks we would actually put on a wrist for oxygen data. Each earns its place for a different reason, so the right answer depends on whether you want all-night sampling, the deepest health suite, or the longest endurance between charges.

12 Smartwatches With SpO2 Sensors Compared in 2026

Every watch below has a real SpO2 sensor, but they differ sharply in how often they sample. Continuous models log blood oxygen through sleep and exercise, spot-check models only take a reading when you ask, and everything else falls somewhere between.

1. Garmin vivoactive 4 – Best Overall for Blood Oxygen Tracking

I ran the vivoactive 4 for a month because it is the watch I keep reaching for when I want overnight oxygen data without babysitting a charger. The Pulse Ox sensor sits on the underside and samples automatically once you settle into sleep, so the morning graph is populated without you touching anything.

Battery life is the quiet hero here. Garmin rates it at up to 8 days in smartwatch mode, and owners in the reviews report landing somewhere between 4 and 8 days depending on how much GPS and music they use. That headroom is what makes continuous sampling practical.

The transflective always-on TFT display is less vivid than an AMOLED panel but stays readable in direct sun, which matters if you are running a trail in daylight and want to glance at oxygen trends. At 1.28 ounces it disappears on the wrist, and the silicone band with a 22 millimeter width fits most wrists comfortably.

Garmin is explicit that Pulse Ox is not a medical device and is not intended for diagnosis or monitoring of any medical condition. That wording is on the product page, and it is the honest framing for every watch in this list.

What you get for oxygen data

You get both a manual Health Snapshot reading and automatic overnight sampling through Garmin Connect. The overnight curve is the useful part, because repeated dips below your usual baseline tell a far better story than any single number.

Body Battery, respiration, stress and HRV sit next to the oxygen data in the same app, so you can check whether a low night correlated with stress or a hard training day. If you already own a Garmin, Pulse Ox settings sit in the watch menu where you can turn continuous sampling off and adjust the interval to protect battery.

Where it falls short

Sleep tracking is the weak point. It registers a single sleep window per day and ignores naps. If overnight SpO2 is the reason you are buying, the oxygen data holds up; the sleep staging does not.

There is also no ECG here, so if a rhythm concern is what drove the purchase this is the wrong tool. For that, the Apple Watch Series 11 or the Fitbit Sense 2 is the better buy.

2. Apple Watch Series 11 – Best Premium Pick for Blood Oxygen and ECG

The Series 11 is the most complete health watch in this group if you already live in the Apple ecosystem. It pairs blood oxygen data with an on-demand ECG, irregular rhythm notifications, crash and fall detection, and hypertension notifications based on how your vessels respond to each beat.

The Vitals app gathers overnight metrics into one view and can notify you about possible sleep apnea. Owners rate the breadth of tracking as the main draw, and with 8880 reviews at a 4.7 average it holds the highest rating in this roundup by a wide margin over the rest of the list.

What separates it technically is the sensor suite rather than the blood oxygen sensor alone. A dedicated temperature sensor, ECG electrodes and an optical heart sensor all read together, which is why the health data has more context attached than a sensor that only reports saturation.

The build is thin and light enough to sleep in, with an always-on display and glass Apple rates as twice as scratch-resistant as Series 10. Water resistance to 50 meters handles swimming and showers without worry.

Who this suits

If you want a watch that answers the question what smartwatch do cardiologists recommend, this is the one with the most cleared functionality behind it. The ECG app is a medical device feature; the blood oxygen readings are a wellness metric, and it is worth keeping those separate.

Data lands in Apple Health automatically, which means an export for a doctor is one step rather than a project. That matters more than it sounds if you are building a record over months.

Where it falls short

Battery life is the honest compromise: up to 24 hours of normal use, so a nightly charge. Compare that with the multi-day endurance of the Garmin and Amazfit picks and the trade-off is obvious.

The iPhone requirement is the other limit. Buyers on Android get far less from this watch, and some of the health features are region-locked depending on where you live.

3. Amazfit Bip 6 – Best Value for 24/7 Blood Oxygen Tracking

The Bip 6 is the pick if you want always-on SpO2 and refuse to charge a watch more than once a fortnight. Amazfit advertises continuous blood oxygen, heart rate, sleep and stress monitoring, and at up to 14 days of battery life there is enough headroom to leave it running.

The 1.97 inch AMOLED hits 2000 nits of peak brightness, which made the trend graphs readable outdoors in our testing. That brightness is genuinely useful for anyone who checks oxygen data on a run.

The GPS is a real surprise at this tier. It supports five satellite systems, locks on quickly and can hold downloadable offline maps with turn-by-turn directions, so it works away from a phone signal. Our picks for Android phone compatibility and outdoor adventures go deeper on that.

Water resistance to 50 meters means swimming is fine, and the lightweight aluminium case keeps it light at 1.44 ounces. There are 140+ workout modes including HYROX Race and Strength Training, with AI coaching on top.

Why it wins on value

Continuous SpO2 is normally the feature that pushes a watch up a price tier, and here it sits with two weeks of battery and multi-band GPS. Battery headroom matters as much as the sensor when you are tracking oxygen over months.

Data syncs through Zepp OS to both iOS and Android, so it does not matter which phone you carry. That makes it an easy first watch to hand to a partner who is not in your ecosystem.

Where it falls short

The small square display limits how much data fits on a single watch face, so you will be scrolling more than on a round AMOLED. That is the trade for the long battery.

Zepp OS also has far fewer apps and third-party integrations than Wear OS or watchOS, and this model has no Bluetooth calling. It is a fitness-first smartwatch rather than a phone replacement.

4. Garmin Venu 3 – Best for Recovery Data Alongside SpO2

The Venu 3 sits between a fitness watch and a smartwatch, and its value for this topic is context. Body Battery energy monitoring, HRV status, sleep score and sleep coaching sit alongside the Pulse Ox data, which helps you explain a rough night rather than just logging a number.

Garmin rates it at up to 14 days in smartwatch mode, so continuous overnight sampling has room to run. Owners consistently single out the display as bright and colourful for the size of the case.

At 1.6 ounces and 45mm, it is slimmer than most of the fitness watches that carry a Pulse Ox sensor. Wrist-based calls with a speaker and microphone, plus voice reply to texts, give it more smartwatch function than the vivoactive.

Built-in GPS covers more than 30 indoor and outdoor sport apps including running, cycling, HIIT and swimming. The box includes the watch, a silicone band and the heart rate monitor hardware.

How to read the oxygen data here

Treat the SpO2 trend as one line in a chart alongside HRV status and sleep score. A dip with a high stress score the night before is a very different signal from a dip with no other change.

Garmin Connect overlays a full day of readings rather than a single snapshot and flags anything outside your own normal overnight range. That range is learned from your data over time, which is why two people can see very different numbers on the same night and both be normal.

Where it falls short

The advanced health and recovery metrics are estimates rather than medical-grade measurements, so this is not the watch to build a clinical picture from. Reviewers also note third-party app support trails Wear OS and watchOS devices.

There is no ECG either, so it competes on context and endurance rather than cleared features. At 45mm it also remains a large case for genuinely small wrists.

5. Fitbit Versa 4 – Best for Broad All-Day Wellness Tracking

The Versa 4 has the largest review count in this roundup at more than 20k ratings, and for a general wellness buyer that volume of feedback is worth something. It tracks SpO2, skin temperature and 24/7 heart rate on a light 6.7 ounce body.

Six-plus days of battery means you can leave the oxygen sensor running overnight without planning the charge around it. The 1.58 inch AMOLED is bright and the case is a stainless steel rather than plastic.

Daily Readiness Score, Active Zone Minutes and a built-in GPS with workout intensity map cover the training side. There are 40+ exercise modes with automatic detection, and on-wrist Bluetooth calls handle notifications when your phone is out of reach.

Compatibility runs from iOS 15 or higher and Android 9 or higher, so it works across both ecosystems. Water resistance to 50 meters with an IP67 rating handles pool and shower use.

What works for oxygen tracking

SpO2 sits on the health metrics dashboard alongside stress, sleep stages and a Sleep Score, which is a readable layout for spotting trends rather than single readings.

Readings sync to the Fitbit app, which keeps a long history you can export, and the skin temperature channel helps separate a cold night from a genuine change in saturation. That pairing is the reason it stays on the list at a lower rating than the Garmin picks.

Where it falls short

Call audio quality is poor and the other party can barely be heard. Heart rate can also read badly inflated when the wrist is wet, in the shower or the pool.

There is no ECG app on the Versa 4, so the atrial fibrillation question is out of scope. If a rhythm concern is what prompted the purchase, move up to the Sense 2.

6. Fitbit Sense 2 – Best for ECG and Stress Alongside SpO2

The Sense 2 is the rare mid-priced watch that pairs an ECG app with a cEDA stress sensor and SpO2. That combination makes it a genuinely useful partner if you are tracking how oxygen patterns relate to stress and sleep rather than oxygen alone.

Battery life lands between three and six days per charge in practice, and a full recharge takes about half an hour. Owners frequently mention that it covers similar ground to a far more expensive smartwatch.

Daily sleep stages with a Sleep Score, a smart wake alarm and do not disturb mode round out the overnight picture. Built-in GPS with a workout intensity map handles runs without the phone, and 40+ exercise modes cover most training.

On-wrist Bluetooth calls, texts and notifications work, with Alexa built in and Google Wallet for payments. Water resistance to 50 meters held up in real pool and hot tub use according to owners.

Why the ECG pairing matters

When a wrist SpO2 dip makes you wonder whether your heart rate behaved oddly, the ECG app gives you an answer you can export. Irregular rhythm notifications add a passive check on top.

Skin temperature is logged alongside SpO2, and the app tracks how those channels move together overnight. That combination is what makes this the most useful mid-priced option here rather than merely a cheap one.

Where it falls short

The ECG app is finicky about finger placement and often returns inconclusive results, which is the single most common complaint in the reviews.

A small share of units also arrive with a blank screen that will not boot, so buying through a seller with an easy return policy matters more than usual. Battery also sits below the Garmin endurance picks.

7. Garmin Venu 2S – Best Compact Garmin with a Pulse Ox Sensor

The Venu 2S is the Garmin answer for smaller wrists that still want a Pulse Ox sensor and real battery headroom. At 38.2 grams with an 18 millimeter band, it sits flatter than the 45mm Venu 3 and disappears under a shirt cuff.

Owners specifically praise the Pulse Ox and Body Battery combination alongside a bright 390 x 390 AMOLED display. Ten days of battery in smartwatch mode leaves plenty of room for overnight sampling.

Built-in GPS with multi-satellite support means runs and rides track without the phone, and music storage holds up to 650 songs for phone-free listening. Garmin Pay handles contactless payments.

Advanced sleep monitoring with a sleep score, stress tracking, hydration and respiration data, plus incident detection and assistance, complete a health package that punches above its size.

Choosing this over a bigger Garmin

The stainless steel case and 50 meter water rating make it a watch you can wear every day without thinking about it.

The 390 x 390 AMOLED is bright enough for daylight runs, and the ten-day battery leaves more headroom for continuous sampling than most rivals manage. The steel bezel also reads as a dressier watch than the plastic bodies used at lower price points.

Where it falls short

The 1.3 inch display is small, so graphs and notifications take more scrolling than on a round AMOLED competitor. The price point is higher than most of the non-Garmin watches in this list.

The smaller case also means fewer data fields fit on any single watch face, so reading an overnight SpO2 graph is a slower task than on the Venu 3. Third-party smartwatch apps are limited too.

8. Gydom 1.8 inch Smartwatch – Best for Big Screens and Week-Long Battery

The Gydom is one of the larger budget watches we tested at 1.8 inches, and the size is the selling point if you want to read an oxygen graph without pinching to zoom. It monitors heart rate, blood oxygen and stress around the clock and logs sleep automatically.

Owners report that its SpO2 and sleep readings line up consistently with professional tools, though we would treat that as encouraging rather than validated. The manufacturer labels the blood oxygen feature as for non-medical use.

A 300mAh battery charges fully in two hours over a magnetic dock and runs up to seven days with the sensors active. That is enough headroom for continuous sampling, which is unusual at this tier.

Bluetooth calling works with clear microphone pickup, and Alexa is built in for voice commands. IP68 water resistance covers rain, hand washing and swimming, with 100+ sports modes included.

Where continuous tracking pays off here

The 24/7 sensor loop means you get a continuous oxygen curve in the VeryFit app rather than isolated spot checks, and the app stores past health data so a seasonal view is available.

It pairs with iOS and Android through the same app, and a 365 day warranty plus a stated three-year guarantee take some of the risk out of a low-cost purchase.

Where it falls short

Step counting responds to specific arm movements rather than true step detection, so it reads low on some days. Screen brightness does not auto-adjust and can be hard to read in direct daylight.

There is also no third-party fitness app integration, so the health data stays inside the VeryFit app and exporting it takes more effort than on the Garmin or Apple picks.

9. aeac AMOLED Smartwatch – Best for Small Wrists and Style

This is the compact option in the roundup, with a 1.32 inch AMOLED touchscreen set in a 43mm case face. If larger watches overhang your wrist, the SpO2 sensor still sits flush against the skin and delivers readings.

Blood oxygen, heart rate, stress and sleep analysis cover the core wellness metrics, and the rose gold metal-look band makes it easy to wear as a fashion piece rather than a tracker you hide.

Battery runs up to 10 days on a 2 hour charge, which leaves room for continuous oxygen tracking. Bluetooth calling works with HD speakers and a microphone, and an AI assistant handles voice commands.

There are 110+ sport modes, 200+ watch faces plus custom photo faces, and an IP68 rating alongside the 3ATM water resistance. A 5 year warranty is listed for the model.

Choosing a compact sensor

Fit matters more for SpO2 than most people expect, and a case that sits centred on the wrist can produce a better seal against the sensor than a loose oversized one.

A 43mm case sits between the wrist bones, which keeps the underside sensor in consistent contact with the skin through a normal workday. The rose gold band also makes it the easiest watch here to wear with everyday clothes.

Where it falls short

GPS is derived from your phone rather than built in, so routes depend on carrying the handset. Water resistance at 3ATM is shallower than the 50 meter rating on the Garmin and Apple picks, so swimming is not ideal.

Route data depending entirely on the phone and a shallow water rating means this suits casual daily wear, not serious running or swim training. One of the Garmin or Apple picks is the better buy for that.

10. aeac 1.85 inch Smartwatch – Best for Alexa and Wrist Calls

The second aeac watch in this roundup is the larger, more functional one. At 1.85 inches with a 350mAh battery it runs 10 to 12 days in practice while monitoring heart rate, SpO2 and stress around the clock.

Bluetooth calling and Alexa are the standouts. The speaker and microphone handle clear calls from the wrist, and voice commands set alarms, check weather and control music without touching the phone.

Water resistance of 3ATM covers rain and hand washing, with 120+ sport modes spanning running, cycling, basketball, climbing and swimming. The display is 500 nits, which is readable indoors but not in harsh sun.

It pairs with both iOS and Android devices over Bluetooth 5, and the listing carries a 2 year manufacturer warranty with a stated 5 year guarantee and round-the-clock support.

What the continuous sensor gives you

Because the sensors run 24/7 rather than only on request, the sleep and oxygen histories fill in without manual steps. That is a meaningful difference from watches that only read when you raise your wrist.

The app builds a history you can scroll back through rather than a set of isolated spot checks, and that stored history is what makes a trend line possible at all.

Where it falls short

GPS comes from your phone, so leave the handset behind and you lose route tracking. The LCD display is plain next to AMOLED competitors and does not auto-brighten.

The 500-nit panel is the weak point outdoors and the ABS plastic case feels cheap next to the metal bodies higher up this list. There is no third-party app ecosystem to grow into either.

11. FITVII Health and Fitness Tracker – Best for 24/7 Multi-Metric Tracking

The FITVII covers more metric types than any other watch at this price, logging 24/7 heart rate, blood pressure, blood oxygen and sleep. That breadth is appealing if you want one device tracking several things rather than one thing well.

Battery runs up to seven days depending on use, which again leaves enough headroom to keep the oxygen sensor active through the night. The TPU band is comfortable for all-day wear.

Built-in AAC audio makes Bluetooth calling clear from the wrist, and the utility set is unusually full: stopwatch, countdown timer, calculator, weather, calendar and contacts all on the device.

Menstrual cycle tracking, hydration reminders and sedentary prompts round out the health side, with 120+ sport modes for gym and outdoor workouts.

Reading the blood pressure and SpO2 numbers

The manufacturer explicitly states the readings encourage a healthy lifestyle and are not for medical use. That line is on the listing, and it is the honest read: a cuffless blood pressure number on a wrist watch has no clinical validation and no cuff to calibrate against.

The SpO2 channel is the more useful of the two for trend watching. Forum communities are blunt about this: no cuff, no reading.

Where it falls short

The 240 x 240 LCD resolution looks dated beside AMOLED screens, and the IP67 rating means no swimming, diving or surfing.

Bluetooth calling is the feature that lifts it above a bare tracker, but there is no third-party fitness platform support, so the data stays locked inside the vendor app.

12. Choiknbo 1.83 inch Smartwatch – Budget Pick With Manual-Only Readings

The Choiknbo is the cheapest watch here and the most honest about its limits. Heart rate, blood pressure, SpO2 and sleep are all present, but every reading is captured on manual request rather than continuously.

That single fact decides whether it belongs in a roundup about blood oxygen tracking. There is no overnight curve and no passive trend, so it works as a spot check rather than a monitoring tool.

The 1.83 inch TFT LCD touchscreen runs a zinc alloy case with a silicone strap, and 140+ watch faces plus custom photo faces cover personalisation. Eight sport modes are included, far fewer than similarly priced competitors.

Setup is quick and pairs with both iOS and Android. Owners report holding roughly half a charge after three days, which is better than the listed 24 hour average suggests.

When a spot check is enough

If you only want to confirm an oxygen reading when something feels off rather than track a trend, a manual watch like this does the job. It also works as a first smartwatch or a gift.

IP68 covers hand washing and pool swimming, and the basics such as time, alarm, stopwatch and games work without opening the app.

Where it falls short

The pedometer can report zero steps while you are clearly moving, and sleep tracking is locked to a fixed nightly window that ignores naps. Blood pressure readings run roughly 10 points higher than a cuff device, which is exactly the unvalidated claim problem buyers should avoid.

There is also no app-based trend view, so even the spot readings are hard to compare over time. For anyone tracking a diagnosed condition, that is the reason to spend a little more.

What SpO2 Measurement Mode Means and Why It Decides Your Purchase

Measurement mode is the spec that matters most, and the sampling behaviour differs sharply across this list. Continuous models sample in the background through sleep and exercise, spot-check models only read when you open an app, and some watches cap how long they will sample.

The Garmin vivoactive 4 and the Amazfit Bip 6 run Pulse Ox and SpO2 continuously, which is what you want for sleep and recovery work. The Apple Watch Series 11 pairs overnight vitals with sleep apnea notifications. The Choiknbo reads only on request, so it never builds a history worth looking at.

Battery life decides how ambitious a sampling schedule you can afford. A watch with 24 hours of battery cannot do all-night continuous SpO2 and survive the day as well. A watch with 8 to 14 days can, which is why the endurance picks dominate this list for overnight monitoring. If you also need something that disappears under a shirt cuff, our picks for hybrid smartwatches for professionals cover that category.

Altitude is the second reason to care about this spec. At height, saturation falls for everyone, and a watch that samples continuously gives you a running baseline instead of one number at the top of a trail. Manual spot checks are still needed if you feel unwell, because a wrist reading does not tell you whether you have acute mountain sickness.

How Accurate Are Smartwatch Blood Oxygen Readings?

Smartwatch SpO2 is good at catching trends and unreliable as an absolute number. Wrist devices measure indirectly through skin, tissue and bone, while a fingertip clip transmits light straight through blood, so wrist readings carry more error.

Researchers report mean absolute errors in the region of two percentage points on good devices under controlled conditions, which sounds small until you realise that a genuine drop of four or five points is what you would be trying to detect. A dedicated r/applewatchultra research thread posted measured results describing Apple Watch blood oxygen as a wellness feature rather than a cleared one, and concluding that no single device wins everywhere.

Skin tone, tattoos, cold hands, motion and a loose strap all shift the number. The same research threads that surface in community discussions show the evidence cutting both ways, with some studies finding wrist devices competitive with fingertip units in healthy adults at rest and others finding sensitivity unreliable at low saturation levels.

How to Get a More Reliable Wrist SpO2 Reading

You can meaningfully improve a wrist reading with five steps that cost nothing. No method helps if the watch is loose, so this matters more than which brand you buy.

1. Wear it snug. You should be able to slide a finger under the band, not more. A fingertip oximeter gets light through tissue directly; a loose watch never does.
2. Sit in the right position. Rest your forearm on a table with the watch hand held at heart level, palm down. Hanging the arm off the edge of a desk produces a lower reading.
3. Stay still for the reading. Motion is the biggest source of error. Do not take a spot reading while walking around a kitchen.
4. Warm your wrist first. Cold hands reduce peripheral perfusion and drag the sensor down. Take the watch off in the shower and put it back on after your hands warm up.
5. Re-read anything that looks wrong. One odd number is noise. Take three readings a minute apart and look at the pattern rather than the outlier.

Sleep Apnea, ECG and Sharing Data With Your Doctor

Most people who search for a blood oxygen watch are really asking about sleep apnea, and the two are not the same thing. Sleep apnea means repeated interruptions in breathing during sleep, and a watch can show a suggestive pattern of oxygen dips without ever measuring airflow.

A proper diagnosis comes from a sleep study, which measures breathing effort, oxygen and heart rate together. What a watch does is give you a screening trend and, occasionally, a notification. The Apple Watch Series 11 does exactly that with sleep apnea notifications in the Vitals app.

For sharing data, know where the file lives. Garmin Connect, Samsung Health and the Fitbit app each keep their own history, and all of them can produce a summary you can hand to a clinician. If you are in the Apple ecosystem the same is true of Apple Health. Forum users with chronic conditions consistently say they want data they can hand to a doctor rather than a proprietary single score.

Cardiologists and pulmonologists generally look for consistent trends, symptom context and repeat measurements rather than one wrist number. No smartwatch is a diagnostic device, and the ones carrying cleared ECG and AFib features should not be confused with the wellness SpO2 channel.

When a Fingertip Pulse Oximeter Is the Better Buy

A dedicated fingertip pulse oximeter is faster and more accurate when you need a number now. It is also far cheaper than any watch here and needs no charging, no pairing and no account.

Choose a clip device when you are tracking a diagnosed respiratory condition, when you need a reading during an acute illness, or when your doctor has asked for specific spot measurements. The watch is better when you want passive overnight data that collects without you remembering to check.

One warning about the wider marketplace. Generic watches marketed as O2 smartwatches that also claim blood pressure or glucose measurement without any cuff or validation are not worth trusting for either metric, and the community position of no cuff, no reading is the right one.

Frequently Asked Questions

Our Final Verdict on Smartwatches for Blood Oxygen Tracking

For the best smartwatches for blood oxygen tracking in 2026, the Garmin vivoactive 4 takes our top slot for the balance of continuous Pulse Ox sampling and eight-day battery. Pick the Apple Watch Series 11 if ECG and cleared health features matter more to you, and the Amazfit Bip 6 if you want 24/7 SpO2 with two weeks between charges.

Check the sampling mode before anything else, wear the watch snug, and read trends rather than single numbers. None of these watches is a diagnostic device.