Heavy Duty 14mil Mylar Stencil Sheets - .014" Thick Polyester Sheet 8.5" x 11" (5-PACK) .014" Thick (14 mils) Strong, Rigid Material Can be cut with X-Acto knife or Hot Stencil Knife. Can be cleaned and reused over and over. Solvent resistant, even stands up to paint thinner. Same material also used for reeds in goose calls.