44mm – Fits 140-210mm wrists.
Space Gray aluminum case Built-in GPS, GLONASS, Galileo, and QZSS S4 with 64-bit dual-core processor. W3 Apple wireless chip. Barometric altimeter. Capacity 16GB. Optical heart sensor. Electrical heart sensor. Improved accelerometer up to 32 g‑forces. Improved gyroscope. Ambient light sensor. LTPO OLED Retina display with Force Touch (1000 nits). Digital Crown with haptic feedback. Louder speaker. Ion-X strengthened glass. Sapphire crystal and ceramic back. Wi-Fi (802.11b/g/n 2.4GHz). Bluetooth 5.0. Built-in rechargeable lithium-ion battery. Up to 18 hours of battery life. Water resistant 50 meters. watchOS 5.