Hudson Bearings stud mounted ball transfer. 1-inch main ball rotates on eighty 1/8-inches support balls. Nylon main ball used for non-marking applications. Carbon steel housing material. Ball support cup is hardened and plated. Protective cover assures low torque and longevity. Threaded stem size: 5/16-18. Carbon steel units are sealed and lubricated to ensure maximum life, unless otherwise specified. Nylon main balls are machined, hardened, and non-marring. 35 pounds load capacity. Common applications: air cargo, shears, robotics, military logistics, store fixtures, die handling, laser and plasma cutters, glass and metal manufacturing, medical devices, caster substitution.