Strong, lightweight and compact. Has a baked-on finish. Can accept plastic or cloth sheeting up to 8 mils thick & can be used with foam rails, side packs, heavy-duty or standard zippers. Should be placed every 8' - 10' or closer if there is a lot of air movement. Patented twist-locking, spring-loaded design. No tape, no ladders, no damage. Works in positive & negative air. Tough, steel construction. Supports 80 lb. For residential or commercial jobs.