4 shower door rollers (4 upper rollers and 4 lower rollers).Screw cover included. Spring mechanism - Also compatible with curved doors. Design with screws and plastic caps.Composition: plastic, nylon and stainless steel.Width of wheels: 6 mm. Minimum hole size in glass: 11mm. Maximum glass thickness: 6mm.These individual pulleys are suitable for shower doors with the center of the hole 18mm from the edge of the glass. 4 shower door rollers (4 upper rollers and 4 lower rollers). Screw cover included. Spring mechanism - Also compatible with curved doors. Design with screws and plastic caps. Composition: plastic, nylon and stainless steel. Wheel dimensions (diameter x thickness): Caster diameter: 23 mm - Wheel width: wheels: 6mm. Minimum hole size in glass: 11mm. Maximum glass thickness: 6 mm. Glass thickness: 4 to 6 mm. Compatible with most shower enclosures. Shower enclosures and sauna cabins. These individual pulleys are suitable for shower doors whose center of the hole is 18 mm from the edge of the glass. Contents: 8 pulleys for shower door shower: 4 upper pulleys and 4 lower pulleys.