Fitbit Charge HR Heart Rate & Activity Fitness Monitor Wristband - Black - Small Type: Fitness Band Color: Black Size: Small Features: Device tracks your sleep and wakes you with a silent, vibrating alarm Specification: SmartTrack automatic exercise recognition Power Source: Bluetooth technology automatically syncs data to your computer or other device Battery Life: Caller ID enables call notifications right on your wrist Operating Environment: Water-resistant device ensures durability