1. This shower door roller set includes 8 single - wheel rollers, with 4 top rollers and 4 bottom rollers. It is suitable for replacing the rollers of shower doors. 2. The wheel has a diameter of 25 mm and a width of 6 mm. The minimum glass installation hole is 11 mm, and the maximum glass thickness is 6 mm. The distance from the center of the installation hole to the glass edge is 18 mm. 3. The shower door rollers are made of brass rods and ABS plastics, which are rust - resistant, sturdy and durable. The set includes screws and plastic covers. 4. These single - wheel shower door rollers are suitable for glass shower doors. This sliding door roller set can help the door slide more easily. 5. It is a convenient hardware accessory for sliding glass shower doors. The bathroom passage door is relatively easy to move and install, and it can save space by moving the door.