Caster; 6×2 Rigid Fork (Hi-Polished Stainless); 6×2 Sirius DUA Premium Polyurethane/Aluminum Wheel (Donut; White) (ESD); 6203 Stainless Steel Precision Ball Bearings and Stainless Steel Top Hat Bushings; 4×4.5 Top Plate; Do not use Nylock nuts.