Ensure your child is safe when learning to ride. Gives your child the best start to gaining their balance and confidence on two wheels. Includes everything you'll need to install the training wheels on a bike with 12-20 inch wheel.Easy to install. Suits 12- 20 inch wheel bicycle. Designed exclusively for single-speed bicycles, not designed for multi-speed bicycles. Specifications: Item name: Training wheels Color: Black/blue/pink Material: PVC+metal Size: Wheel outer diameter: 11.5cm Wheel inner diameter: 9mm Package Includes: 2 x Training wheels 2 x Brackets 1 x Wrench 2 x Screw 4 x Gasket Note: - There might be little error of size for manual measurement. - The colors deviation might differ due to different monitor settings, please kindly understand.