Upgraded Version: Adjustable floor and wall guide. It provides stability and smoothness in the sliding door. The smooth roller does not damage your door. Beautiful and practical. And thanks to its simplicity of installation, it is perfect for both expert and non-expert users. Material: The sliding door wheels have been made of sturdy steel and nylon external parts to provide superior quality to the product. The external bearings provide a smooth surface capable of reducing the friction caused by the sliding of iron doors; In addition, they offer durability and impact resistance. Easy to Install: The sliding barn door kit is able to keep the door perfectly balanced on the roller guide, preventing wobbling. The roller wheels can also be used as a sliding door guide so that the sliding barn door hardware will not produce noise and be balanced. for sliding garage doors, interior door and gate.etc Usages: Nylon wheels as sliding door guide (2pcs*40mm x 60mm) for sliding door, electric