Series 3 (GPS + Cellular) Features 
Note: (Only GPS Wi-Fi working for Cellular you have to confirm with your operator)

Gold aluminum case 
Built-in GPS and GLONASS
Faster dual-core processor 
W2 chip
Barometric altimeter 
Capacity 16GB
Heart rate sensor 
Accelerometer and gyroscope
Water resistant 50 meters2 
Ion-X strengthened glass
Composite back 
Wi-Fi (802.11b/g/n 2.4GHz)
Bluetooth 4.2 
Up to 18 hours of battery life
watchOS 4

Dimensions

Height: 42.5mm
Width: 36.4mm
Depth: 11.4mm
Case Weight (GPS + Cellular): 34.9g