This set of stabilization assistants young teachers they have developed a useful sense of balance on the bike. Please ensure the safety of your children without holding back to the saddle.Wheel diameter: 4.33 inches. Universal training wheels are suitable for 12/14/16/18/20" kids bikes. Tip: Only for one speed bicycles (can not be installed on bikes with switches) and supports riders up to 100 pounds.These bike training wheels are made of high-quality plastic and rubber that are non-slip, load resistant, provide stability and help children to ride a bike without wearing any clothes. Light weight and noiseless.Easy to install, all installation instruction is included, you have more choices to adjust the height.