Anti-slip, wear-, good stability:Quiet bike training wheels let kids enjoy riding without making any noise Safety and confidence: is and more stable for beginners This set of stabilizers can help young learners until they develop a usable sense of balance on a bike, which can your child's safety and improve confidence Universal training wheels for 12/14/16/18/20 inch kids bikes Note: Bicycle training wheels are only suitable for single speed bicycles (cannot be installed on bicycles with derailleurs) Colour:Blue Material:Metal Package Contents: 4 x Bicycle training wheel bracket ( with installation tools) Only the above package content, other products are not included. Note: Light reflection 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.