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 wheel on your bike. Material: These bicycle 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, stable; The high-quality materials used are non-slip and silent. 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 and give them a good start with confidence and love for the sport. 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.