GORIN Button Ring Lock - Black Button-type ring lock (keyless). Recommended for those who often lose or forget their bicycle keys; a passcode button type. Unlocks with a push of a 4-digit passcode. Safety knob adopted. . *The passcode cannot be changed. *Before installation, please check if the passcode tag is attached to the main unit and use the number written on it. [Product Name] Button Ring Lock GR-500 [Product Category] Bicycle lock, rear wheel lock, ring lock, horseshoe lock, keyless lock [Manufacturer] GORIN [Color] Black [Part Number] GR500 [Suitable Size] Back fork diameter 13mm Suitable for general light-duty bicycles, city cycles, mama-chari, etc. *Please contact the bicycle manufacturer for details, as it may not be possible to install on some bicycles (due to back fork dimensions, etc.) or may hit your foot while riding. [Caution] Not for use with sports-type road bikes, cross bikes, or MTBs.