Included: 2 x wheels, 2 x brackets, 2 x screws, 2 x washers, 2 x screw caps, 2 fixing codes, 1 x wrench; Complete installation hardware provided for easy and quick attachment of training wheels to your bicycle. Material: Bicycle training wheels constructed from high-quality plastic and rubber. Wheel diameter: 11 cm, thickness: 2.9 cm. Compatible with most 12-inch to 20-inch single-speed bicycles. Thickened design: Enhanced thickness improves wear resistance and stability. High-quality materials provide non-slip performance and quiet operation, offering a safer and more stable riding experience for beginners. Safe and stable: These rear training wheels deliver necessary support and balance for children learning to ride, helping them build confidence and enjoy cycling. 100% money-back guarantee: If you have any concerns regarding product quality, a 60-day return option is available for a full refund. A replacement can also be requested at no additional cost.