These self-seal 13" x 16" + 4" Bottom Gusset Poly mailers are the perfect packaging material to protect your bulky apparel, bags, textbooks, or blankets from dirt and moisture during shipping and handling. Expansion poly mailers feature 4" gusseted depth which make packing and shipping bulky items such as binders, books, jackets, and catalogs possible and convenient. Our expansion poly mailing envelopes have a peel-and-seal lip that provides a secure, tamper-evident closure and is the ultimate lightweight, low-cost shipping solution for bulky, non-fragile items.