Turning freestanding wire shelving into mobile storage, our four-pack of non-marking rubber threaded casters allow you to transport items with ease.They are compatible with Shelving Inc. brand posts only. If you have another brand, please use thesestem casters. Sold in set of 4, available individuallyhere Ideal for transit over rough surfaces Bolts with 12 threads per inch screw into bottom of Shelving Inc. brand 1"dia posts Swivels 360 degrees for easy steering Step-lock brakes control movement Non-marking, won't scuff floors For stability, not recommended for use with 8"d wire shelving