Expandable self-sealing 10" x 13" poly mailers with a bottom gusset of 2" are the perfect packaging material to protect bulky product. These products might include apparel, bags, textbooks, or blankets products you surly want to keep dirt and moisture away from during shipping and handling.  These expansion poly mailers have a strong peel-and-seal lip that provides a secure, tamper-evident closure. Expandable poly mailers are a lightweight, low-cost shipping solution for bulky, non-fragile items that can overall help reduce your shipping cost. Custom Printing Available.