Rival Tech - 5 layer Shrink film that is a material made up of polymer plastic film. When heat is applied,Website:http://www.rival-tech-bj.com, it shrinks tightly over whatever it is covering. Heat can be applied with a handheld heat gun (electric or gas), or the product and film can pass through a heat tunnel on a conveyor. Shrink wrap is applied over or around the intended item, often by automated equipment. It is then heated by a heat gun or sent through a shrink tunnel or oven for shrinking. We provide different size and thickness film to meeting different needs.