Glossary

Milliampere-hours, the unit manufacturers use for the size of a rechargeable cell. It describes how much charge the cell holds, which is a tank size and not a range. Converting it to hours requires knowing the draw, and product listings almost never state one.

See alsoStated runtimeStandby

The battery figure a manufacturer prints, produced under conditions the manufacturer selected and usually does not describe. It is the maker’s claim, not a measurement made by anybody else, and this site never presents one as more than that. Where a listing states none, this site records that too.

See alsomAhStandbyAlways-on display

The state a device spends most of its life in: awake enough to keep time and hold a connection, asleep enough to cost almost nothing. A stated runtime in days is mostly a statement about how cheap a device’s standby is. Anything that interrupts standby, such as a notification or a sensor sample, is the thing that spends the battery.

See alsoStated runtimePairingBluetooth version

A setting that keeps a dimmed version of the watch face lit continuously rather than waking the screen on a wrist raise. It is the single largest controllable draw on a wrist device. Two smartwatch listings in this catalog state one, and neither of them states a battery figure alongside it.

See alsoAMOLEDStated runtime

A display type in which each pixel emits its own light, so black pixels cost nothing and bright ones cost a great deal. That makes power use a function of what is on screen rather than a fixed number. Several listings here state AMOLED panels and state their size in inches.

See alsoAlways-on displayStated runtime

A satellite positioning receiver, stated on several watch listings as built-in. Holding a fix is the heaviest sustained load a wrist device carries, well above a screen at normal brightness. A watch that quotes one runtime figure without separating GPS hours from everyday hours has combined two very different numbers.

See alsoStated runtimeStandby

An optical component that shines light into skin and reads what comes back, named in many listings here as a heart rate monitor. This site records it as a feature the manufacturer states the product has. It does not restate it as something that establishes anything about the person wearing it, and health decisions belong with a clinician.

See alsoSpO2 sensorWearable

A second optical function, stated on some listings as SpO2 monitoring, using light at more than one wavelength. As with any sensor named in a listing, this site treats the name as a statement that the feature exists and nothing further. Consumer devices are not medical devices unless the manufacturer states a specific clearance.

See alsoHeart rate sensorWearable

A feature name used by listings that describe sleep tracking broken into named stages. It is recorded here as a product feature and not as a description of what a device knows about your night. Several listings in this catalog state sleep tracking, a sleep monitor or a sleep score, all of which are the manufacturer’s own labels.

See alsoReadiness scoreCompanion app

A single composite number some manufacturers produce from their own inputs, using their own method, under their own name. Body Battery, energy score and daily readiness are three such names appearing in listings here. They are not comparable across brands and this site does not treat any of them as a finding.

See alsoSleep stagingSubscription tier

Active noise canceling: mics sample the sound around you and the earbud plays an opposing signal. It runs continuously and costs battery the whole time it is on. Two earbud listings here state it as a feature of what you hear, and one states it only for the microphone, which is a different thing.

See alsoTransparency modeStated runtime

The inverse of noise canceling: the mics pass outside sound through to the driver so you can hear the room without removing the buds. It is a listed feature where a product has it, and like noise canceling it runs mics and processing continuously.

See alsoANCCodec

The compression scheme audio travels in over a Bluetooth link. Which codecs a pair of earbuds supports affects quality and, to a smaller degree, power. None of the twelve earbud listings in this catalog states a codec, which is worth noticing given how often they state everything else.

See alsoBluetooth versionPairing

A two-character ingress class from a defined test standard: the first character covers solids, the second liquids, and an X means that part was not tested. IP68 and IPX5 are both classes, but they are not the same claim. A class is a test result, not a permission to do anything in particular.

See alsoATM ratingWater resistance versus waterproof

A pressure class used on watches, expressed in atmospheres, from a static bench test. It describes pressure held under laboratory conditions, not movement through water, temperature changes or soap. One smartwatch listing in this catalog states 3ATM and none of the others states any class at all.

See alsoIP ratingWater resistance versus waterproof

Water resistance is a stated class from a specific test. Waterproof is a word with no test behind it, which is why serious manufacturers avoid it. Neither an IP class nor an ATM class tells you whether a maker supports swimming, showering or diving with their product, and only the maker can answer that.

See alsoIP ratingATM rating

The revision of the wireless specification a product implements, stated as a number such as 5.3 or 5.4. A higher version generally brings efficiency and connection improvements, but a version number alone does not tell you which optional features a product implements. Several listings here state a version and nothing else about the radio.

See alsoPairingCodec

The one-time handshake that lets two Bluetooth devices recognize each other afterward. It is where a companion app usually first appears, and where an account requirement, if there is one, tends to surface. Two wired listings in this catalog skip this step entirely because there is no radio in them.

See alsoCompanion appBluetooth version

The phone application a wearable talks to, where settings live and where readings are read. On a screenless device it is the only interface there is. An app is also the place a fee, a tier or an account requirement can appear later without the product listing ever having mentioned one.

See alsoSubscription tierTrial periodFirmware

A named level of paid access to features in a companion app. This site records which of five models a listing describes and never records an amount, because amounts change and a stale figure misleads. One listing here uses the phrase no app fee for standard features, which describes a tier boundary without defining it.

See alsoCompanion appTrial period

A stated window during which paid features are included with a purchase. Three listings in this catalog state a three-month included membership. None of the three states which features stop when the window closes, which is the part worth asking about before it does.

See alsoSubscription tierCompanion app

The software running on the device itself, updated through the companion app. A firmware update can change how power is managed, which means a stated runtime describes the device as shipped rather than the device you will be holding in a year. No listing in this catalog mentions firmware at all.

See alsoCompanion appStated runtime

Transcutaneous electrical nerve stimulation, a class of device regulated as a medical device. Ten products in this catalog belong to that class and are listed here as product records only. This site publishes no information about using a device of this class; that belongs to the manufacturer’s instructions and to a clinician.

See alsoEMSElectrode pad

Electrical muscle stimulation, another class of device regulated as a medical device, and a term appearing in some listings alongside TENS. As with TENS, this site records only what a listing states about the object and gives no guidance of any kind on use. Whether such a device is appropriate for anyone is a question for a clinician.

See alsoTENSElectrode pad

The consumable adhesive part supplied with an electrical stimulation unit, counted in listings as a quantity in the box. This site records the stated count as a formal specification, in the same way it records a stated mode count. It records nothing else about them.

See alsoTENSEMS

Any device designed to be worn rather than carried, which in this catalog spans five places on the body and six product categories. The word covers everything from a wired pair of headphones to a regulated medical device, which is exactly why this site sorts by stated runtime and stated fee rather than by that word.

See alsoStated runtimeSubscription tierHeart rate sensor