Pinch-track zipper protects contents from dirt and moisture Single-track zipper expands the width of the bag. Meets FDA requirements for food applications. Reclosable and reusable. Sizes listed are the inside usable dimensions of the bag. Office Depot Brand 4-Mil Reclosable Poly Bags, 3in. x 4in., Case Of 1,000 is one of many Reclosable Poly Bags available through Office Depot. Made by Office Depot.