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: 6mm. Includes screws with caps. Spring action design, suitable for curved showers. Comes with nut and plastic cover. Application: The glass door roller is suitable for most shower enclosures, helps prevent the door from swinging. Allows the door to slide smoothly, effortlessly, and safely. Note: These shower door rollers fit glass shower doors with a distance of 18mm between the center of the hole and the glass edge. Castors for shower and massage cubicles, bathrooms, Jacuzzis, and furniture fittings. Thanks to these rollers, door and sliding systems operate easily and smoothly. Distance between the center of the hole and the edge of the glass: 18mm. Wheel diameter: 23mm. Glass hole size: 11mm. Wheel width: 5mm. Contents: 4 upper rollers 4 lower rollers 8 screws 8 plastic covers