Getwow 10-Pack Silicon Fastener Ring for Fitbit Flex Wireless Activity + Sleep Wristband The size of the silicone fasteners are specially designed to fit the Fitbit Flex Wireless Activity + Sleep Wristband Silicon Fastener Ring - designed specially to protect the clasp loose and band fall off Colorful, secure your wristband in style and get it looks fun Comfortable and durable silicon made Perfect fit for your Fitbit Flex activity tracker and comfortable wearing experience