Includes: 2 Wheels, 2 Brackets, 2 Screws, 2 Washers, 2 Nuts, 2 Fixing Codes, 1 Wrench; We provide complete installation tools so it is easy and quick to install the training wheels on your on the bike. Material: These bicycle training wheels are made of high-quality plastic and rubber. Wheel diameter 11cm, thickness 2.9cm; suitable for most 12-inch to 20-inch single-speed bicycles. Thickened design: The thickened design makes the wheel more wear-resistant and stable; it is made of high-quality materials, non-slip and noiseless. For beginners, it will be safer and more stable. SAFE AND STABLE These rear wheels provide the necessary safety and stability for children's first biking attempts and give them a head start, confidence and a love for the sport. Guarantee: If you have any questions about this product, you can contact us by email and we will reply to you within 24 hours. If the purchased product has quality defects, we offer a 60-day guarantee and you can also request free re-delivery.