Shower door rollers: 4 rollers of 23 mm (2 upper rollers, 2 lower rollers). Installed at the top and bottom of the shower door. Roller material: The roller is made of ABS and zinc alloy. It is durable. Roller set: each roller is equipped with a screw cap. It is easy to slip on and clean. Glass hole size: roller suitable for glass thickness: 4-6 mm, glass opening: 12-14mm. Applicable scene: These shower door rollers are suitable for most shower rooms, it is convenient to open and close the shower door. Material: ABS + zinc alloy Quantity: 4 pieces (two upper towers, two lower towers) Size: Wheel diameter: 23 mm, glass thickness: 4-6 mm, glass opening: 12-14mm Durable material: The roller is made of ABS with zinc alloy. He is strong and brilliant. Roller Accessories: The roller is secured in place with screws and covered with a screw cap, making it beautiful and easy to clean. Area of application: The roller is suitable for flat sliding shower doors and curved sliding doors. Package includes: 4 x shower door rollers