1. Fits 16-29inch size children's bikes so you can move them from bike to bike as your kids get older. 2. the of your children and prevent accidental injuries when learning to ride. 3. Provide more confidence for your boy to learn to ride a bike while they know they are safe, which improves their learning efficiency. 4. Accessories are supplied to facilitate installation. 5. Strong metal supports to provide additional stability and security. Description: This practical training wheel is suitable for 16 to 29-inch bicycles, which to provide the necessary security and stability for your children. Children are , more confident that they would like to ride a bike, and even faster than they learn. Specification: Suitable for:16-29 inch bicycle wheels Colour:Random colors (red+orange+yellow+green+blue+black+purple) random mode is Material:PU+Metal Size:Diameter: about 11cm Package Contents: 2* Bicycle wheels 2* support 1* Installation parts set Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.