High Quality Materials: Made of high quality galvanized steel, sturdy, durable, waterproof and anti-corrosion. Good wear resistance and chemical stability, can be used for a long time. Powerful Load: Heavy-duty cold-rolled steel rack brings huge load-bearing capacity to your project, and a single wheel can bear a maximum load of 300 kg / 661 lbs. Features: Double bearing, with good sliding and good stability, providing greater flexibility, reducing vibration, reducing noise and smooth operation. Size:The wheel diameter is 50mm, the total height of the wheel is 60mm, the V-groove depth is 10mm.V-shaped groove can fit the reverse track perfectly. Widely Used: Reverse Tracks, Garden Doors, Roller Shutters, Patio Sliding Doors, Industrial Machinery , wire rope guides, c shelves containers, baby gates, dog gates, etc.