Yens Poly Mailers 100pk ENVELOPES SHIPPING BAGS Self-seal Poly Mailers. Tear-proof, Water-resistant and Postage-saving Lightweight Plastic Shipping Envelopes (M5:12X15.5) Yens Only sold by FantasyBuy or Amazon High Quality Self Sealing Mailers. Water, Tear and Puncture resistant. The Dark Grey inner layer provides confidentiality Pressure sensitive adhesive provides a high strength durable closure, water and dirt resistant