Features:

• Swimproof²
• IP6X dust resistant²
• Always-On Retina display Up to 1000 nits
• Blood Oxygen app¹⁶
• ECG app¹⁷
• High and low heart rate notifications
• Irregular rhythm notification⁵
• Temperature sensing¹⁸, Cycle tracking with retrospective ovulation estimates¹³
• Emergency SOS⁴, International emergency calling¹⁹, Fall Detection, Crash Detection⁴ 
• Cellular available⁷ Family Setup — pair multiple watches with one iPhone⁸