Fitbit Flex 2 Fitness Tracker Wristband (FB403BK) - US Version - BlackThe Fitbit Flex 2 Fitness Tracker Wristband (US Version). Wristband comes in Black. Model: FB403BK Features: Thin and sleek design provides you the benefits of the FitBit without a bulky watch Tracker hides in band, pendants and bangles Swim proof so you never have to take it off and can track your swimming SmartTrack automatically recognizes select workouts and records them to your Fitbit app Get call and text notifications via unique vibration