●☆Wheels diameter:4.54 inch. Universal training wheels fits for 12/14/16/18/20 inch bicycles. Tips: For Single Speed Bikes Only (Cannot Be Installed On Bikes with Derailleurs) and Supports Riders up to 100 Pounds . ●☆These bicycle training wheels are made of high quality plastic and rubber which it is anti-slip, wear resistant, providing stability and help to ride a bike without fear. Light weight and noiseless. ●Note: please use under adult supervision.