4" X 2" Rigid Caster Heavy Duty Polyurethane on Steel Hub 700lb Each 4" X 2" Rigid Caster Heavy Duty Polyurethane on Steel Hub 700lb Each Feature: 3/4" Roller Bearing with 1/2" ID Bushing (Manufacture will provide zerk fitting in the wheel or axle) Material: Heavy Duty Polyurethane on Steel Hub Capacity: 700lbs