The OEM Fitbit FB150 USB Bluetooth Wireless Sync Dongle is a black plastic dongle designed specifically for Fitbit devices. It allows for wireless syncing of Fitbit activity trackers to compatible devices for data transfer. Measuring 1 inch in length, 1 inch in height, and 0.25 inches in width, this lightweight dongle is easy to use and portable for on-the-go syncing during gym workouts or training sessions.