Griffin Technology GRFGB40137 - Ribbon Wristband for Fitness Trackers Stretch ribbon is comfortable all day long. Inline pocket holds fitness tracker securely. Easily adjusts to fit most wrists up to 8.27 (21 cm) around. Use with Fitbit Flex, Fitbit One, Sony SmartBand, and other fitness trackers measuring up to 20 mm wide X 48 mm long X 10 mm thick.