6" x 2" Inch Rigid Caster - Semi-Steel Cast Iron Wheel - 1,200 Lbs Capacity. This series is made of 1/4 thick cold rolled steel; designed, formed, and welded for optimal mobility and made to withstand the rigors and abuse typically seen in Medium duty applications. Double Ball raceways and a 5/8 nut & king-pin are standard features; however we also offer a rivet kingpin version & a kingpinless version. Poupular applications may include; various carts, trucks, dollies, racks & equipment, for almost every industry including industrial, warehousing, hospitality, institutional, food service, food processing, retail display, and countless other medium duty applications.