RocFly New Replacement Bluetooth USB Wireless Sync Dongle Compatible with Fitbit Flex/Force/One/Charge/Surge/Charge HR Activity Trackers 100% new and high quality. Plug into USB port Compatible with Fitbit Flex/Force/One/Charge/Surge/Charge HR Activiity Trackers NOTE: It not work for FITBIT ZIP MODEL, please pay attention to it before you are buying. Note: The best syncing distance between the fitbit tracker and dongle is within 1m