This hook is designed to slide into the underside rail of the Seville Classic UltraHD line of workbenches. The hook is designed to be rotated into the rail on the underside of the desk and support a 12 inch wire rack. The wire rack hook is intended to hold a top rack to the underside of the desk. The wire rack hangers are intended to hold multiple wire racks below one another like shown in the images. I used these racks for my project: https://www.homedepot.com/p/Everbilt-6-ft-x-12-in-Regular-Duty-Wire-Shelf-90241/314184170