Danger: Confined Space Keep Out Unless, Reusable Polyethylene Stencil, 63 mil Thick, 10" x 7" Make as many signs as you want, with just one stencil. Made of 63 mil thick polyethylene. Easy to clean. Use with our quick drying ink (sold separately), suitable for concrete, block, steel doors, pipes and insulation to permanently mark facility with safety messages. These stencils outlast low-cost oil board stencils, which quickly become sodden and not reusable. Inside of stencil is polished, and burr-free.