DuraShelf 96" x 36" Grid Top Shelving is a tough all-plastic industrial storage solution. Made of high-density polyethylene (HDPE), DuraShelf features easy no-tool assembly. It will not rust, is chemically resistant, and is ideal for HAZMAT storage or maintenance rooms. DuraShelf is UV treated and can be used indoors or outdoors. Each shelf is 2-5/8" thick with a grid top pattern that allows liquids to flow through and promotes air circulation. Shelves are spaced 21-1/2" apart. An Add-On option is available if you already own a DuraShelf 96" x 36" unit. Add-On Units add 24" to the overall height of a DuraShelf system.