8 Shower Rooms Cabins Roller &Shower Door Enclosures Rollers Runners Wheels Pulleys (20MM-27MM) (Roller diameter 20MM) A Set of 8 Pcs Single Shower Door Rollers (4 upper rollers and 4 bottom rollers). Diameter of the wheel:20MM/22MM 23MM /25MM/27MM; Width of the wheel: 6mm. Minimum Hole size in the glass: 11mm. Maximum glass thickness: 6mm. Material: Plastic, Nylon, A Plastic, Nylon BS and stainless steel. Comes with screw cover caps. Spring loaded action can also fit curved showers. Designed with a nut and a plastic cover