It uses Griptex®, a proprietary gripping technology. Think of the textured surface of GLAD Press'n Seal® wrap as having thousands of tiny hills and valleys. Only when you apply pressure do the valleys seal to the desired location. The sealing actually works with the help of the primary ingredients typically found in chewing gum — an old idea now applied to wrap! These ingredients have been approved by the FDA for over 35 years and are frequently used for labels found on fruits and vegetables. Griptex® technology allows GLAD Press'n Seal® wrap to seal to plastic, paper, Styrofoam® containers, metal, wood and many other surfaces.