Etekcity 500 pcs Premium PM4 10&rdquo; x 13&rdquo; 10x13 Self-Sealing White Poly Mailers/Mailing Shipping Envelopes/Bags Pack of 500 10" x13" poly mailing envelopes with water, tear and puncture resistant High-efficiency mailers are perfect for shipping a wide variety of non-fragile items The silver inner layer provides confidentiality Pressure sensitive adhesive provides a high strength durable closure, water and dirt resistant Thick poly material, durable yet with lightweight, saved you a bunch on shipping cost!