Red Documents Enclosed Envelopes Features. Pressure sensitive envelopes secure and protect documents that are attached to the outside of shipments. Preprinted with specialty use messages on heavy 2 Mil poly. Hot melt adhesive backing provides strong adhesion to paper and corrugated products. Envelopes open along the firstSpecifications. Color Red. Material 2 Mil Poly. Dimension 12 W x 10 L