Material: The shower door roller is made of stainless steel and PA material, the wheels are made of POM, which is durable and quiet, stable for a long service life.Size : wheel diameter: 23mm; wheel width: 5mm; minimum hole size in glass: 11mm; maximum glass thickness: 6 mm.Screws With caps for the screws. Spring action, also suitable for curved showers. With a nut and a plastic cover.Application - The glass door roller is suitable for most shower enclosures, prevents the door from swinging. Let the door slide smoothly, effortlessly and safely.Note: These shower door rollers fit glass shower doors that have a distance between the center of the hole and the 18 mm glass edge. Castors for shower and massage cubicles, bathrooms, Jacuzzis and even for furniture fittings. Thanks to our rollers, door and sliding syst can be easily and smoothly. The distance between the center of the hole and the edge of the glass should be 18 mm. Size: Wheel diameter: 23mm. Glass hole size: 11mm. Wheel width: 5mm. Contents: 4 upper rollers. 4 lower rollers. 8 screws. 8 plastic covers .