[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. When shopping, please pay attention to the size and dimensions of the product to ensure that it meets your needs. In the title and , we have provided detailed information about the product, including its features and specifications We want you to be completely satisfied with your purchase, so if you have any questions or concerns, please dont hesitate to contact us. We are here to help and will do our best to assist you. Thank you for choosing our product. We hope you enjoy it