Hudson Bearings flying saucer ball transfer. Multi-directional rolling surface. Can be recessed into the surface of the application forming a smooth. Integral mounting holes for ease of installation. Nylon main ball is available for non-marking applications. Carbon steel units are sealed and lubricated to ensure maximum life, unless otherwise specified. 100 pounds load capacity. Ball material: nylon. Housing material: carbon steel. Nylon main balls are machined, hardened, and non-marring. 3-21/32-inches diameter.