DIA-COMPE Caliper Brake? Dual pivot caliper brake?A6061 Cold forged aluminum arm?dimension 61mm-79mm? Silver BlaBlue Red Gold? BAA Safty standard approved?192g/wheelFor Road Bicycle ,folding Bike ,City Bike,Retro Bicycle …(If it is used for the rear brake, you need to add a nut washer yourself,)