Two Adjustable Sizes: Large size for 6.7"-8.1" wrist, Small size for 5.5"- 6.7" wrist.(Only for Fitbit Charge 2, Charge 3 is not compatible)Soft Material: These bands for fitbit charge 2 hr are made from flexible elastomer, sweat resistant & water resistant.No Worry about Falling off: These replacement wristbands for fitbit charge 2 design with metal clasps on both ends, which locks onto the charge 2 precisely and securely.Hassle Free: Simple to install and remove, no tool required.