1.77Mil Lightweight & Durable Poly MailersSave on shipping cost with these lightweight bags These 1.77 Mil poly mailers are the perfect for shipping lightweight materials. With water and tamper resistance, and a self-sealing lip with a synthetic rubber adhesive, these provide a safe and secure way to ship your packages. Not only are these mailers secure, these lightweight bags will save you money on shipping cost. Available Poly Mailer Sizes:17.5 x 21″19.5 x 24″ Item Specification: Black Exterior, Black Interior (Interior color of mailer is subject to change).Dual side 1.77 millimeter thickness (+/- 5%)Adhesive: Synthetic rubber – Hotmelt, ¼” minimum.High adhesive seal strip—packages are tightly secured after 3-5 minutes sealed.Lip Size: 1.75” +/- ¼”.Approved by UPS, FedEx, and USPS.Provides excellent protection during shipments.Ideal for shipping lightweight items.Inks, Stamps, Labels adheres easily.Water proof and moisture proof.