Carpet Glides are designed to perfectly fit a single ball castor wheel, in either 50mm or 63mm, to stop the glide falling off like many other castor cups, the wheel simply snaps into position when pushed into the cup and stays in position. The smooth base allows it to be easily moved across carpeted floors. Manufactured in the UK to a high quality. Each pack contains 4 Carpet glides. The ideal solution to prevent castors marking or damaging flooring.