GPS + Cellular model lets you call, text, and get directions without your phone Measure your blood oxygen with an all-new sensor and app Check your heart rhythm with the ECG app The Always-On Retina display is 2.5x brighter outdoors when your wrist is down S6 SiP is up to 20% faster than Series 5 5GHz Wi-Fi and U1 Ultra Wideband chip Track your daily activity on Apple Watch and see your trends in the Fitness app on iPhone