Helps make moving wire shelving easy with the caster kit for wire shelving. Snap-ring around stem makes for easy attachment. Using casters may reduce load capacity for the shelving unit. Four 3″ Casters (2 Locking).?Bumpers help keep shelving unit from damaging walls. 125 lbs. Per Caster (500 lbs. total). Caster/Glide/Wheel: Grip Ring Stem Single Wheel Casters; Color: Black; Stem Type: Grip Ring; Weight Capacity (text): 125 lbs Per Caster (500 lbs total).