iWatch Ultra 2 is Always-On Retina display Up to 3000 nits, 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-g accelerometer, Third-generation optical heart sensor, Irregular rhythm notifications, Sleep stages, Temperature sensing, Water temperature sensor, Compass with Waypoints and Backtrack. More features: Apple Pay GymKit, Recreational dive to 40m, USB-C magnetic fast charging cable, Precision Finding for iPhone2, International emergency calling, High-speed water sports.