Solid shelves are a solution where dirt, dust and spills are a potential issue. The solid flat surface allows for storage from small to large items and the marine edge perimeter prevents spillage. The double hemmed steel gives the solid shelf excellent strength characteristics. Add-on units consist of 4 shelves, 2 posts and 8 shelf clamps. Additional shelves may be purchased separately. Units with Add-On kit cannot be made mobile. Finish: Galvanized Steel.