Tenzapost co-extruded opaque polythene mailing bags offer an extra layer of protection from dust, damp and tampering without increasing the size or weight of the consignment. They are fast and easy to use, cost-effective and available in a wide range of sizes to suit the differing dimensions of contents without excessive use of plastic packaging. They are also increasingly popular with the rapidly-increasing mail order and e-commerce markets as they are suitable for post and courier delivery. The high opacity of the dual layer polythene film protects the identity of the contents and any accompanying documentation. A permanent adhesive, peel-and-seal envelope flap prevents accidental or deliberate opening and resealing of the package during transit and will clearly expose where any attempt might have been made to do so.