Product Linkbr br About this item br Operating System watchOS 4br Memory Storage Capacity 16 GBbr Special Feature ECG, Sleep Monitor, Activity Tracker, GPS, Bluetooth, Heart Rate Monitor, Wireless, Daily Workout Memory, Notifications, Music Player, Blood Pressure MonitorECG, Sleep Monitor, Activity Tracker, GPS, Bluetooth, Heart Rate Monitor, Wireless, Daily W… See morebr Connectivity Technology Bluetooth, gpsbr Wireless Communication Standard Bluetoothbr Battery Cell Composition Lithium Ionbr GPS Truebr Shape Heart,Irregularbr Screen Size 1.