Office Chair Caster Resistant polyurethane material, less noise, it won't scratch or mark the floor, protects your carpet and any hardwood floors Universal standard stem size: 11mm (7/16") diameter, 22mm (7/8") length Heavy duty office chair caster wheels maximum weight rating: 110 lbs for single, 550 lbs for 5 set The casters apply to office chair, filing cabinet, shopping trolley, computer desk swivel chair, wardrobe Easy to replace, just pull off the old ones by hands and stick in the new ones. No screws or other attachments