We offer a large selection of Dura-Bag Mailers. You can search many types of Dura-Bag Expandable Mailers, Dura-Bag Flat Mailers and Dura-Bag Self-Sealing Flat Mailers. Dura-Bag Expandable Mailer is fiberglass strands laminated to kraft paper create tough mailers that resist tears and punctures. Lightweight to reduce shipping cost.