Smartwatches powered with Wear OS by Google work with iPhone and Android Phones Extend your battery life for multiple days with new, smart battery modes; magnetic USB rapid charger included; charge up to 80% in under an hour Heart Rate & Activity Tracking using, Google Fit; Built-in GPS for distance tracking; Swimproof design 5ATM; responses from Google Assistant - it's your own personal Google, always ready to help; Speed through checkout with your watch using Google Pay Case size: 43mm; Band size: 20mm; interchangeable with Michael Kors 20mm bands; Screen Size: 1.19'' display with 390 x 390 resolution; touchscreen functionality; Connectivity: Bluetooth 4.2 LE, NFC, WiFi; wireless syncing;