Found the following on Apple's product page for an individual watch.
Series 1
Series 1 Features
Series 1
- Height: 42.5mm
- Width: 36.4mm
- Depth: 10.5mm
- Case Weight: 30g
- Height: 42.5mm
- Width: 36.4mm
- Depth: 11.4mm
- Case Weight: 34.2g
Series 1 Features
- Gold aluminum case
- S1P dual-core processor
- Splash resistant1
- Ion-X glass
- OLED Retina display with Force Touch (450 nits)
- Composite back
- Digital Crown
- Heart rate sensor, accelerometer, and gyroscope
- Ambient light sensor
- Speaker and microphone
- Wi-Fi (802.11b/g/n 2.4GHz)
- Bluetooth 4.0
- Up to 18 hours of battery life3
- watchOS 3
- Gold aluminum case
- S2 dual-core processor
- Built-in GPS
- Water resistant 50 meters2
- Ion-X glass
- 2x brighter OLED Retina display with Force Touch (1000 nits)
- Ceramic back
- Digital Crown
- Heart rate sensor, accelerometer, and gyroscope
- Ambient light sensor
- Direct fire speaker and microphone
- Wi-Fi (802.11b/g/n 2.4GHz)
- Bluetooth 4.0
- Up to 18 hours of battery life3
- watchOS 3