Redesigned and re-engineered with built-in electrical and optical heart sensor, a new Digital Crown with haptic feedback & varying heart rate notifications. For fitness fans, it has New Breathe watch faces, auto workout detection, new yoga & hiking workouts & advanced running features. Plus, new head-to-head competitions, activity sharing with friends, personalised coaching, monthly challenges and achievement awards. On top of all these amazing features, its also swim-proof. The GPS Apple Watch S4 has a 30% larger display and 50% louder speaker than the S3. For those always on the go, use Walkie-Talkie, make phone calls and send messages. Listen to Apple Music, podcasts and use Siri in new ways right from your wrist. Connectivity 16GB memory. iOS operating system. Bluetooth 5 connection. Wi-Fi. Display information 40mm AMOLED screen. Touchscreen. Battery Typical usage time of up to 1 day. Low usage time of up to 0.75 day. Physical specification Size: medium. T10.7mm. Weight 30.1g. Features Water resistant. Dust resistant. Make calls. Answer calls. Read texts and reply to texts. Read emails and reply to emails. Receive social network notifications. View calendar. Displays weather. Music player. Heart rate monitor. Pedometer. Accelerometer. GPS. Accessories included: Case, Band, 1m Magnetic Charging Cable and 5W USB Power adapter.