Always-on retina display up to 3000nits, Three-microphone array with beamforming and wind noise mitigation, cycle tracking, activity tracker, GPS, voice control, heart rate monitor. Battery: Fast charging. Built-in rechargeable lithium-ion battery. Up to 36 hours normal use. Up to 72 hours in Low power mode. Faster on-device Siri with health data access. Sensors: Blood oxygen sensor and app Footnote, Ambient light sensor. High accelerometer, third generation optical heart sensor, irregular rhythm notifications, sleep stages, temperature sensing, water temperature sensor, compass with waypoints and backtrack. Apple pay gymkit. Recreational dive to 40m. USB-C magnetic fast charging cable. Precision finding for iphone, international emergency calling, high-speed water sports.