Improved version: Adjustable floor and wall guide. It provides stability and fluidity in the sliding door. the smooth roller does not sadden your door. Beautiful and practical. And with its simple installation, it's perfect for both expert and non-expert users. Material: The sliding door wheels have been constructed from heavy-duty steel and nylon outer parts to provide quality superior to the product. External bearings provide a smooth surface capable of reducing friction caused by sliding iron doors; In addition, they provide durability and impact resistance. Humanization: 1. Hot-dip galvanizing, 2. Zinc layer thickness: 120g 3. Salt spray test time: 72 hours (not rust) 4. Error: 50mm. Application: electric door in wheel / nylon sleeve wheel for sliding door / iron door by wheel / electric door guide wheel / track wheel / pulley. Easy to Install: The sliding kit barn door roller is able to keep the door perfectly balanced on the roller guide, preventing swinging. The rolling wheels can also be used as a sliding door guide so that the sliding barn door hardware is noiseless and balanced. for sliding garage doors, interior door and gate.etc Uses: Nylon wheels as sliding door guide (2 units* 30mm x 40mm) for sliding door, electric door, sliding rollers, garage , sliding doors, sliding door wheels, conveyor rollers or conveyor roller, paddle/pallet wheels, worn roller spare parts | Applications: industrial and general. Great replacements for the old or damaged one Used as electric door top wheel, nylon clamp wheel for panoramic door, iron door wheel , electric gate guide wheel, crawler wheel and pulley Sturdy carbon steel body and nylon roller make sliding smooth and quiet; Invisible rotating wheel on one vertical side not only makes the sliding smoother and quieter, but also saves more space;