Etekcity 500 pcs Premium PM3 9&rdquo; x 12&rdquo;9x12 Self-Sealing White Poly Mailers/Mailing Shipping Envelopes/Bags Pack of 500 9" x 12" 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!