50 Pack - 9x12 WHITE POLY MAILERS ENVELOPES BAGS 9 x 12(USA MADE) High Quality PolyAir Self Sealing Mailers. Water, Tear and Puncture resistant. The silver inner layer provides confidentiality Pressure sensitive adhesive provides a high strength durable closure, water and dirt resistant High-efficiency mailers are perfect for shipping a wide variety of non-fragile items.