Amazfit T-Rex 3 (48 mm) / Samsung Galaxy Watch6 Classic (47 mm)

There is also a night display mode.

According to Samsung, the display is larger than on the Watch4 Classic and the rotating bezel is 15% thinner. Sapphire crystal resists scratches; the bezel partly surrounds the edge of the screen.

The 22 mm strap is a standard width and can be swapped.

10 ATM means withstanding the pressure of 100 metres of still water for up to 10 minutes. Breath-hold training and testing are downloaded through the Zepp app.

A full charge takes about 3 hours; a magnetic charging base is in the box but no USB-C cable. Low-temperature mode gives 28 hours with GPS on and 32 days with it off. The maximum GPS mode works only in hiking and climbing modes.

Dual-band positioning receives two frequencies from the satellites to reduce drift from reflected signals among tall buildings and dense trees; it uses more battery. Automatic mode switches settings based on signal strength.

The watch offers an altitude assistant, storm alerts, compass, sunrise/sunset and tide information, and prompts for blood-oxygen readings at high altitude.

Bioelectrical impedance analysis passes a weak current through the body when two fingers rest on the buttons to estimate muscle, fat and water; it should not be used with a pacemaker or during pregnancy. ECG and blood pressure work only in approved markets through Samsung Health Monitor.

Wi-Fi is used to download software updates without the phone. The watch shows incoming calls but cannot take Bluetooth calls; quick reply works on Android only.

LTE is only on the LTE version; on the Bluetooth version internet and notifications come through the paired phone.

Chest straps, running/cycling power meters and cycling speed/cadence sensors can be paired; data can be exported to apps such as Strava, komoot and Apple Health.

Turning the bezel moves between notifications and tiles without touching the screen; its position is sensed by a 3D Hall sensor.

Samsung’s fast-charge testing used the magnetic fast-charging cable and a separately sold 25 W adapter. Battery life varies with network, usage and watch face.

Setup needs a phone with Google Mobile Services, Android 10 or later and more than 1.5 GB of memory; it does not work with an iPhone.

5ATM corresponds to 50 metres for 10 minutes; it is not suitable for diving or high-pressure water. IP68 covers 1.5 metres in fresh water for 30 minutes.

Thickness is measured without the health sensors.