Sleep tracking & sleep score See the quality of each night’s sleep by measuring heart rate, time asleep, time awake, time in deep and REM sleep and restlessness. Heart rate tracking Use 24/7 heart rate tracking to better track calorie burn, optimise effort during workouts, see your resting heart rate trends and cardio fitness level. Get your notifications Get notifications for calls, texts, calendar events and apps - plus send quick replies and voice replies right from your wrist. Always-on display mode See real-time exercise stats and cheque the time with just a glance - even when your hands are full. Turn the mode off to be more discreet. Use amazon Alexa built in to get quick news and information, check the weather, set timers and alarms, control your smart home devices and more all through the sound of your voice (third party app may be required; amazon Alexa not available in all countries) Based on your heart rate, time asleep and restlessness, sleep score helps you better understand your sleep quality each night; also track your time in light, deep and REM sleep stages and get personal insights Control your Spotify app, download Pandora stations and add Deezer playlists, plus store and play 300+ songs on your wrist (subscription required; Pandora is us only) With a larger display and an always on option, your information’s always a quick glance away (always on display requires more frequent charging) Track heart rate 24/7, steps, distance, calories burned, hourly activity, active minutes and floors climbed. Syncing range - up to 6.1 meters Works around the clock with 6 plus day battery life (varies with use and other factors) Get a call, text, calendar and smartphone app notifications when your phone is nearby; plus send quick replies and a voice replies on android only. Works with Bluetooth headphones & 200+ leading iOS and Android devices.