Material: Nylon Copper, Good Elasticity, Good Wear Resistance, Corrosion Resistance, Anti-Rust, Stable Quality And Has A Long Service Life. Shower Door Rollers Size: Wheel Diameter: 20mm; Wheel Thickness: 5.5mm. Suitable for 4-6mm glass thickness. Total Length: Approximately 33mm. For Glass Door Openings: 10~12mm; 12mm recommended. Thickness: 4-6mm. DIY Replacement: It is easy and convenient for this door knob DIY replacement; you can easily disassemble it with a screwdriver and replace it with new rollers on glass doors. No noise when opening the shower door and these glass door rollers help it slide smoothly. It is easy to install and maintain. Installed on the top and bottom of the shower door, to make it easy to open and close. Wide Application: For shower doors and massage cabins, bathtubs, jacuzzis or other furniture fittings. Suitable for most shower enclosures, shower stalls and steam rooms. Package Includes: Set of 8 rollers. Over time, the rollers will need to be replaced. A Perfect Spare Part/Replacement.