[HEAVY DUTY CASTERS]:All SY America casters are equipped with roller bearing to provide a smooth and quiet rolling experience.Each caster has a 800 lbs load capacity, and purchasing a set of 4 casters will allow for a 3200 lbs load capacity. [POLYURETHANE TREAD]:Caster has a crowned polyurethane tread chemically bonded to a solid heavy duty cast iron core. Provides good floor protection and quiet rolling operation.Polyurethane casters are suitable for corrosive, oils or greas environments. [THICKENED CASTER YOKE]:The caster yoke surface has a galvanized anti-rust coating.It is made from 1/4" thick cast iron, is designed, formed and welded for optimal mobility and to withstand the rigors and abuses typical for duty caster applications. [MOUNTING BOLT & GREASE FITTINGS]: Our casters are designed for a 3/8” bolt size for mounting, ensuring a secure fit for your equipment. Please note, mounting hardware is not included. They feature convenient zerk fittings on the swivel raceway and axles for easy lubrication, maintaining smooth and silent operation. Ideal for industrial applications requiring regular maintenance. [WIDELY USED]: Caster wheels heavy duty are widely used in tool box, workshop table, steel table, dolly, workbox, dumpster, trolley, institutional equipment and carts, suitable for indoor and outdoor. Green Polyurethane on Cast Iron Caster