Move to the beat of you with Fitbit Alta HR-the heart rate wristband that motivates you to reach your goals in style. Jumpstart your fitness journey with PurePulse heart rate and Smart Track automatic exercise recognition. Track your all-day activity and sleep, stay connected with smartphone notifications, and get friendly Reminders to Move.  Get the power of continuous heart rate in Fitbit's thinnest design, all day, during workouts and beyond .  With heart rate, you can better measure calories burned and use zones (fat burn, cardio, and peak) to find the right workout intensity for your goals.  With PurePulse heart rate-powered sleep stages, automatically track your time spent in light, deep, and REM sleep and take steps toward a better night's sleep.   Battery lithium-polymer. Charging time one to two hours. Using Bluetooth LE wireless technology, Fitbit Alta HR sends smartphone notifications and syncs automatically to computers and 200+ mobile devices. Smartphone notifications may require Android 5.0+. Syncing range: Up to 30 feet Syncing requires Bluetooth LE and Internet connection. Windows 10 computers that do not have Bluetooth LE will need a wireless sync dongle in order to sync. Syncs with Mac OS X 10.6 and up, iPhone 4S and later, iPad 3 gen. and later, Android 4.4 and later, and Windows 10 devices. The Fitbit Alta HR wristband is made of a flexible, durable elastomer material similar to that used in many sports watches. The tracker is made with surgical-grade stainless steel, and the buckle is made with aluminum. Comes with charger/sync cord and original box.