Shelf trucks have gray rust resistant posts.. Shelves have a lifetime warranty against rust and corrosion.Steel Reinforced Plasteel Utility Carts and Shelf Trucks have molded polyethylene steel reinforced plasteel utility carts and shelf trucks (ps1848v64c 4) shelves that are reinforced with a square steel tube frame that is epoxy coated for strength and corrosion resistance. Utility carts have chromate posts and dual handles.