The aluminum case is lightweight and made from 100 percent recycled aerospace-grade alloy. The Sport Band is made from a durable yet surprisingly soft high-performance fluoroelastomer, with an innovative pin-and-tuck closure. Retina display Up to 1000 nits brightness High and low heart rate notifications Irregular rhythm notification1 Cardio fitness notifications Cycle tracking10 Emergency SOS3 International emergency calling Fall detectio Crash Detection3