ALERA-CASTER,WIRE SHELVING,4/ST. Optional Casters For Wire Shelving, 600 lbs./Caster, Gray, 4/Set. Helps make moving wire shelving easy with the caster kit for wire shelving. Snap-ring around stem makes for easy attachment. Four 5" hooded wheels with bumpers supports up to 220 lbs. each. Using casters reduces load capacity for the shelving unit. Stem Type: Snap Ring; Wheel Tread: N/A; Color(s): Gray; Material(s): N/A.