KKBESTPACK offers 10" x 13" Poly bags in sleek black, perfect for shipping envelopes. These self-seal poly mailers are designed to be water, tear, and puncture resistant, ensuring your items are protected during transit. The pressure-sensitive adhesive provides a high-strength durable closure, keeping your packages secure and resistant to water and dirt. Ideal for shipping a variety of items, these poly mailers offer reliability and convenience for your shipping needs.