Q-Ball Renewal Glides retro-fit all existing school furniture, allowing for a quiet, scratch-free function. They have superior flexibility that will work on all flooring types such as carpet, VCT tile, traditional tile, hardwood, rubber and concrete! Q-Ball Renewal Glides require just seconds of your time to permanently install over your existing glide. The Q-Ball glide pays for itself quickly and is backed by a Limited Lifetime Warranty. Choose from the rubber-like PVC surface for a limited-slide function or the replaceable felt fiber surface for a smooth glide function.