Super high quality: Our bicycle auxiliary wheels are made of high quality metal, plastic and rubber materials. Unique design: We are most concerned about the safety of our customers. The exercise bike has a small stand which is more stable and can help young students to cycle until they feel the balance of the bike, so you don't have to worry about the safety of your children. High-quality lightning wheels: non-slip, wear-resistant, stable, the support wheels for the support wheels are 3.0 mm thick. This provides more security and stability for beginners. Black wheels are perfect for any colored bike. Universal and adjustable: support wheels fit 12/14/16/18/20 inch single speed bike with one end rearward-pointing horizontal fork but not suitable for people with semi-horizontal or vertical legs.