For all the features of Fitbit Flex-in-one silicone wrist band, soft and safe material, make it comfortable than the original, harmless, more perfect Unibody design wristband, it is more durable and less likely to be broken, you will not worry about losing track again Movement Specially designed safety pin collar fixed to maintain a stable ring to prevent belt slip, more protection for your safety wrist strap to track all the time A size adjustable strap suitable for most people, not just the parts tracking