[Preferred material]: The outer wheel of the shower door moving pulley is made of wear-resistant nylon material, which is smooth and silent when moving. The internal rolling bearing is made of stainless steel, which is corrosion-resistant and compressive. It can be used for a long time. The thickness of the wheel: 5mm, comes with screws, suitable for 4- 6mm thick shower door. [Product matching]: 12 sets of pulley combinations (including pulleys and matching stainless steel M4 bolts), 8 pulleys with an outer diameter of 23mm and 4 pulleys with an outer diameter of 25mm, matching M4*10mm 12 bolts, according to the bathroom glass sliding door pulley/slide rail The use requirements are reasonable collocation, giving people a more flexible collocation. Easy to install: Use a screwdriver to loosen and remove the worn pulley, then replace it with a new pulley, and tighten the supporting bolts to complete the replacement of a pulley. If more than one pulley is damaged, replace it one by one until all are replaced.