Our shower door rollers are made of a galvanized plastic alloy that is resistant to rust. The plastic alloy ensures smooth sliding and significantly reduces the risk of glass breakage due to collisions. Adjust the wheel height with the top screw (adjustable by 7-8 mm). These shower door rollers fit glass thicknesses of 4-6 mm and glass openings of 12-14 mm. The wheel diameter is 25 mm. Four additional anti-collision blocks are provided to better protect the shower door opening. Additional anti-collision protection is provided to better protect the shower door. A pair of shower door rollers can support approximately 30-35 kg. It is recommended to install a glass door in the load area. You can install multiple spare wheels to distribute the load across each pair of rollers. It is recommended to replace plastic-cased shower door rollers every six months.