Features: Material: High-quality metal, for beginners, it will be safty, more stable, light weight and no noise. Protection: Make sure your child is safe when learning to ride, and let your child get the best start to balance and confidence on two wheels Function: Non-slip, wear-resistant, provide stability, help children ride bicycles, and let children enjoy the fun of riding bicycles. General: The size of the auxiliary wheels is adjustable, suitable for 12-20 inch children single-speed bicycles. Easy to install: Includes everything you need to install. Specifications: Material: Metal Weight: 670g Size: As picture shows Color: Red/Purple/Green/Blue/Pink/Black Package Includes: 1 Set Bike Wheels note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to difference between different monitors, the picture may not reflect the actual color of the item.