Large Size Resealable Plastic Bags are 4 Mil Heavy Duty suited for shipping, packaging, and storage. Bags are ideal for large items and bulk packing, for packing smaller packages into this large thick single bag, for Books and Magazines... Bags are re-usable; sealing is simple and easy with the single track zip closure strip. Organize and protect your items, parts, various sizes or for individual pieces in these thick and large size bags.