About this item ❤Fits: Universal training wheels fits for 12/ 14/ 16/ 18/ 20/ inch children's single speed bicycles/EXCEPT HUFFY Brand Bike(Cannot Be Installed On Bikes with Derailleurs). ❤Material: High-quality ABS wheels, and high-quality steel , Macy training wheels bracket arms are 3.0mm thickness, Wheels diameter approx 13 cm/5.12 inch. These will be more security and stability for beginner. ❤Function:It is anti-slip, wear resistant, providing stability and help children to ride a bike without fear. They can provide the necessary security and stability which it needs in the first road tests on the bike. Gives child the best start to gain their balance and confidence on two wheels. ❤Included: 2 x Bracket Brace Plates,2 x Nuts,2 x Washers,2 x black caps,2 x Shoulder Bolts,2 x Vertical Bracket arms,2 x Wheels,1 x installation instructions. ❤INSTALLATION: Easy to install, all mounting hardware and installation instructions is included, you will have more choices to adjust the height.