Retina display with 1000 nits. Workout and Mindfulness apps. Crash Detection automatically connects with emergency services and notifies emergency contacts. Heart Rate app - notifications for high or low heart rate or an irregular rhythm. Sleep app - tracks sleep and shows sleep trends. WatchOS 10. S8 SIP chip. Built-in GPS. Up to 18 hours of battery life. Water resistant to 50 M. Starlight aluminum case. Starlight sports band with pin-and-tuck closure. Case size: 44mm x 38mm x 10.7mm. M/L Band fits wrists 160mm-210mm in circumference.