Spring-Loaded Design: Allows gates to open and close freely by automatically adjusting height on uneven ground while eliminating gate sagging. Heavy-Duty Caster: The wheel has a maximum load capacity of 440 lbs and can also withstand exposure to chemicals and solvents. Shock Absorption: Easy to move and roll, makes opening and closing the gate easier. Made of premium nylon and metal construction, sturdy and durable. Heavy-duty universal mounting plate with 6 holes for easily attaching to wooden gates or along the horizontal or vertical rails of a farm tubular door. Specification: Material: Nylon + Metal Weight: Approx. 1498 g/52.8oz Caster Diameter: 100mm/4inch Load Capacity: Max.200kg/440lbs Package List:1 * Door Wheel Note:Please allow slight error due to manual measurement. Thanks for your understanding. luckymeet