Track steps, distance, calories burned, and minutes of activity. Operating temperature from -10° to 45° C. Click on the display to view statistics and time via bright OLED; Battery life up to 5 days. Battery life and charge cycles vary depending on usage, Settings, and other factors; Actual results will vary. Radio transceiver: Bluetooth 4.0. Automatically track your sleep time and sleep conditions, and set a silent vibration alarm; The Fitbit Alta band is made of a flexible and durable elastomer material, similar to the elastomer material used in many sports watches. The Alta tracker and buttons are made of surgical-grade stainless steel; Wireless sync: Android and Windows devices. Personalized interchangeable metal, leather and classic straps, sold separately; Battery life up to 5 days. Battery life and charge cycles vary depending on usage, Settings, and other factors; Actual results will vary. Battery type: Lithium polymer. Charging time: one to two hours. Get phone, text and calendar notifications at a glance when the phone is nearby. Synchronization range: up to 45 m