RWM's Freedom 48 series swivel section consists of a heavy duty sealed precision ball bearing that is sealed for life at the factory making it totally maintenance free. It is capable of all radial and thrust loads and offers ultra quiet operation. This ergonomic caster is designed for ease of movement and noise reduction. Mounting Plate available with variety of sizes, the thick top plates increase the versatility and extend the caster life due to enhanced protection of the swivel section. Rivet (Kingpin) is larger in diameter and hydraulically staked to be stronger than any comparable load rated caster in the industry. This eliminates any possibility of kingpin stretch. Rivet welded to reduce vibration rattle. Precision ball bearings are totally sealed to protect against the damaging effects of water, dirt, grit or chemicals. The 48 series is available with a variety of top plates, leg lengths, wheel and brake options. The Maintenance Free Freedom 48 series is the perfect solution for almost any caster application including dollies, waste disposal trucks, warehouse trucks, floor trucks and shop carts. 1/2" Diameter axle, mounting plate size is 4" x 4-1/2" x 1/4"and 2" tread wheel.