Included: 2 x wheels, 2 x brackets, 2 x screws, 2 x washers, 2 x screw caps, 2 mounting codes, 1 x wrench; We provide a complete installation tool, so it's easy to quickly install the training wheels on your bike. Material: These bike training wheels are made of high-quality plastic and rubber. The wheel diameter is 11 cm and the thickness is 2.9 cm; Suitable for most 12 to 20 inch single-speed bikes. Thickened design: thicker design makes the wheels more durable and stable; The high-quality materials used are non-slip and quiet. It will be safer and more stable for beginners. Safe and Stable: These rear wheels provide the necessary safety and stability for children's first cycling attempts, giving them a good start with confidence and love for the sport. 100% MONEY-BACK GUARANTEE: If you have any questions about this product, you can contact us by email and we will reply within 24 hours. If the purchase has any quality defect, we offer a 60-day money-back guarantee, you can also ask for a NEW DELIVERY for free.