Strap fits 145 165mm wrists s2 dual core processor built in gps wi fi 802 11bgn 2 4ghz bluetooth 4 0 requires iphone 5 or later digital crown sapphire crystal 2x brighter oled retina display with force touch 1000 nits ceramic back heart rate sensor accelerometer and gyroscope ambient light sensor direct fire speaker and microphone water resistant 50 metres up to 18 hours of battery life watch os 3