Faster S3 dual-core processors and W2 Apple wireless chips power the Series 3 models, which also feature all the following:
Built-in GPS and GLONASS.
Barometric altimeter.
Water-resistant to 50 meters under ISO standard 22810:2010.
Heart rate sensor.
Accelerometer.
Gyroscope.
Ambient light sensor.
Siri speaks.
Features
Two sizes: 40mm and 44mm.
Always-on display.
Faster S6 chip.
New low-cost SE option.
Blood oxygen monitoring.
New colors.
LTE and non-LTE options
The Apple Watch SE is water-resistant to 50 meters and supports Apple Pay with skin authentication much like prior models, and though it lacks ECG and blood oxygen monitoring, it has the same optical heart rate sensor, gyroscope, and accelerometer so it can monitor steps taken, calories burned, stairs climbed.
