7 x 5 1/2" U.S.A. Ribbon "Packing List Enclosed" Envelopes. Pressure sensitive packing list envelopes secure and protect documents that are attached to the outside of shipments. Pre-printed with patriotic message and/or image on heavy 2 Mil poly. Hot melt adhesive backing provides strong adhesion to paper and corrugated products. Envelopes open along the first dimension.