Our individually-sold, non-marking rubber threaded casters accommodate existing mobile wire shelving with a damaged wheel, as well as solutions without four posts.They are compatible with Shelving Inc. brand posts only. If you have another brand, please use thesestem casters. Sold individually, available in 4-packhere Ideal for transit over rough surfaces Bolt with 12 threads per inch screws into bottom of Shelving Inc. brand 1"dia post Swivels 360 degrees for easy steering Step-lock brake controls movement Non-marking, won't scuff floors For stability, not recommended for use with 8"d wire shelving