2 Mil Adhesive Backed Reclosable Ziplock Bags are perfect for larger documents like shipping information, job tickets or shipments of small parts. They are also excellent for work-in-progress projects where papers are frequently removed, checked, and returned to the zipper bag. These Press-on Envelopes have a pressure-sensitive adhesive backing that sticks to most surfaces. Our Press-on Ziplock Bags are stick on Lock and Press bags, which keeps out moisture, dirt and other contaminats and are made from sturdy 2mil poly film.