Description: Compatibility: The kids bike training wheels are suitable for children's bicycles of 12", 14", 16", 18", and 20", providing the necessary and stability for your child's bike.Adjustable Design: The children bicycle training wheels is available for you to adjust the height according to your child's learning progress for gradually cycling training.Premium Material: Kids auxiliary wheels are made from premium material, anti slip and wear resistant materials. These heavy duty rear wheels are designed to last.Product Dimensions: The kids rear wheels have diameter of 10.9cm or 4.29inch, making it the proper size for most children's bikes.Easy Installation: The children bike training auxiliary wheels come with additional accessories such as a wrench set, easy to install by parents. Specification: Material: Metal, PP Size Chart: Wheel Diameter 10.9cm or 4.29inch Package Includes: 1 Pair of Kids Bicycle Training Wheels with Wrench Set Note: Please allow slightly errors 1-2cm differences due to manual measurement.