Raskullz Flip Up training wheels support your child as they learn how to balance on their bike for the first time. These training wheels are designed to teach balance by hovering up to 1/2 inch off the ground on either side when properly installed. And as your little rider becomes more confident, these training wheels can flip up out of the way. They fit bike tires 12.5-18 inches in diameter and support a maximum rider weight of 50 lbs. The installation manual is easy to follow making installation quick and simple (Not all tools are included for installation).