BACKPACK BOYZ : Halloween Pumpkins Packaging 3.5 Mylar Bag Items are Non-Refundable and Non-Exchangeable. BACKPACK BOYZ : Halloween Pumpkins Packaging 3.5 Mylar Bag In its basic form, Mylar® is a clear material made from polyester resin. The silver effect comes from a lamination to foil or a metalized coating. In addition to ...