MATERIAL: This u groove wheel is made of high quality galvanized steel, strong, waterproof and anti-corrosion SIZE: Wheel diameter is 50mm, wheel inner width is 22mm, outer width is 30mm. Suitable for 19mm round tube orbits LOAD CAPACITY: With 3mm thick bracket, each U-slot gate wheel can hold 300kg load, easy to carry for heavy gates, gliding smoothly and stably Roller bearings: Double ball bearings make the sliding stable and smooth, easy to push the gate PERFECT FOR: Entrance gate, factory gate, sliding fence, dog gate, reverse track, industrial machine, rolling gate, container shelf Product Description These gate wheels U-slot rails are made of high quality steel with galvanization, which is strong, waterproof and anti-corrosion. It is perfect for reverse lane, industrial machine, rolling. door, sliding door, factory door, driveway door, dog door, storage shelf. container. Specifications: Material: Galvanized steel Wheel diameter: 50mm The Wheel inner width: 30mm Wheel outer width: 22mm Bracket size: 68 x 38mm (L x W) Hole distance bolt diameter: 47 x 18mm (L x W) Bracket thickness: 3mm Loading capacity: 300kg Package includes: 4 U-slot door wheels