MOTIVATION ON YOUR WRIST-Earns NikeFuel, a universal way to measure movement for all kinds of activities-Tracks the intensity of your workouts with Nike+ Sessions-Counts steps, enables sleep tracking and tells time-Displays your progress in real time-Keeps you and your friends motivated through Nike+ GroupsPRODUCT DETAILS-Includes two easy-to-insert links (.32 inches / 8mm and .63 inches / 16mm) for a fine-tuned fit.-USB charging cable and sizing tool included.-Ambient light sensor detects environmental light levels and adjusts accordingly.-Bluetooth 4.0 pairing to smart phones (for use with the Nike+ FuelBand app for iOS 6.1 and above, iPhone 4S and above, and iPod Touch 5th generation and above)-Optimized for the web (Mac OSX v10.6 and above / Windows XP, Vista, 7 and 8) and works on iOS devices (iPhone 4S and above, iPod Touch 5th generation and above).-Water-resistant.WARRANTY INFORMATION-The Nike+ FuelBand SE comes with a one-year limited warranty.SENSORS-A built-in 3 axis accelerometer measures your motion all day long.-An ambient light sensor detects environmental light levels. The brighter your environment, the brighter your display.BATTERY-Two Lithium Polymer Batteries. Your Nike+ FuelBand should stay charged for up to four days.IN THE BOX-Nike+ FuelBand-8mm and 16mm links (8mm link is already inserted into your Nike+ FuelBand)-Sizing tool-USB charging cable