T20P Poly Sure Opaque Poly Mailers measure 525mm x 600mm. The co-extruded 45 micron polythene they’re made from is extra strong, lightweight, waterproof, puncture resistant and tear resistant. It is also fully recyclable, 100% degradable and has all messages printed with water-based inks, so as well as adding very little to postal costs, they can reduce damage during transit and impact on the environment. Additionally, all contents are kept secure by the high grade opaque finish, heat sealed edges and tamper evident seal.