Magnetic, high-impact plastic with folding, central hinge that opens every 15 degrees for greater accuracy when reading posts, pipes or signs. Versatile, can also be used on flat surfaces. Folds flat for easy storage. Includes reinforced, perforated, heavy-duty elastic strap for quick and easy fastening to non-metallic posts. 3 yellow vials will plumb or level in both planes at the same time. Shelf Pack includes 6 levels in a display box.