Specification: Color: blue, pink, black Material: PVC Wheel outer diameter: 11.5cm/4.5inch Weight: about 700g Package includes: 2 pieces bicycle auxiliary wheels (including parts) Training wheels Material: high quality rubber wheels and steel bracket. Diameter of training wheels 11.5cm, weight approx. 700 g Safer: Our support arms offer beginners more safety and stability. Only use them to teach your child how to balance the bike. This is a good helper for street sports. Excellent application: for children's single speed bikes of 12, 14, 16, 18, 20 inch bicycles (NOTE: Works only with hub gears. Not compatible with the geared bike) Easy installation: comes with fittings that you can assemble in minutes. The brackets can be adjusted individually, no bending or twisting (NOTE: it will not work with derailleur gears)