Courier bags are made from paper or plastic. Nowadays, most of plastic courier bags are made of 2 or 3 layer with Polyolefin's (HDPE & LDPE) and they are either mono or co-extruded. These bags are designed an open “one side flap” for protecting and delivery products, which an adhesive that is applied to the Seal Flap and is covered with a release liner. When the envelope is ready to be sealed, the release liner is removed to expose the adhesive. The adhesive will immediately bonds to the plastic envelopes and firmly sealed. (The optimum bond is best achieved after 1 hour). A welded pouch or "overlapping pocket" is also available at the back of the courier bags to attach supporting documentation.Lightweight for postage savings. q Water-resistant. q Excellent and High Quality Control q Strong self-sealing performance q High resistance to tear and puncture. q Dirt protection.