ECG Accurate : Provides accurate heart rate data. Exercise chronograph : Recalls exercise time for the last exercise session. Other functions : Time display. S-shaped design : Curves around the wrist for improved comfort and read. Ergonomic chest transmitter : Provides increased comfort. Nike simplified logic : Easy operation with two button use. Water resistant to 30 meters. Face Diameter : 43mm (1.7""). Face Depth : 16mm (0.6""). Includes chest strap and software.