500 10x13 Purpler Polymailers Poly Mailers Shipping Envelopes (500 Pieces) 500 10x13 Purple UneekMailers Self Seal Poly 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