500 (One Hundred S3 (Dimension 7.5" X 10.5") Poly Mailers) Tear-proof, Water-resistant and Postage-saving Lightweight Self-seal Poly Mailers Shipping bags, works perfect for shipping light products, T-Shirts, Cables/Accesories and much more! UPS, FEDEX, USPS, NEWGISTICS, DHL APPROVED Tough and tear-proof poly mailers. Water and tamper resistant poly mailers. High strength seams allow over-stuffing. Postage-saving lightweight poly mailers.