OurtraditionalPoly Mailing Bagsaremade from a co-extruded blend of Low and Linear-Low Density Polyethylene. They come with a Peel-and-seal, permanent adhesive tape on flap. We've also have a line of PERFORATEDPoly Mailing Bags. They feature the same materials and design as our traditional poly mailers except that a perforation has been added for end-user ease-of-use.