1. Product packaging: 2 * auxiliary wheel. 2 * shoulder screws. 2 * screw cap. 2 washers. 2 * lock nuts. 2 * handrails. 1 * key. 2. Super high quality: Our bicycle auxiliary wheels are made of metal materials. made of high quality plastic and rubber. 3. 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 ride the bike until they feel the balance of the bike. so you don't have to worry about the safety of your children. 4. 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. 5.Universal and Adjustable: Support wheels fit 12/14/16/18/20 inch single speed bike with rearward pointing horizontal fork end. but not suitable for people with semi-horizontal or vertical legs.