Converting your freestanding wire shelving into mobile storage is easy with our four-pack of 5" polyurethane threaded casters.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 Best for cold and hot environments and smooth indoor 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 prevent movement Resists chemicals, grease, and oil 1,200 lb weight capacity per set of four For stability, not recommended for use with 8"d wire shelving