training wheels flash mute wheel bicycle stabiliser mounted Kit compatible for bikes of 12 14 16 18 20 Inch， 1 PairThis set of stabilizers assist young learners until they have developed a usable sense of balance on the bicycle. Improve your child's safety and confidence without holding the back of the saddle . Wheels diameter: 4. 33 inch. Universal training wheels fits for 12 14 16 18 20 inch children's bicycles. Tips: For Single Speed Bikes Only (Cannot Be Installed On Bikes with Derailleurs)A few bicycle axles less than 0. 8 inches will not fit and Supports