Heavy-duty Poly Bags are perfect for protecting heavy weight products like industrial parts and tools from dirt, dust and moisture Close bags with twist ties, bag tape or by heat sealing. 100% virgin, high clarity polyethylene film. Meets FDA and USDA specifications for food contact. Sizes listed are the inside usable dimensions of the bag. Office Depot(R) Brand 4-Mil Flat Poly Bags, 20in. x 20in., Case Of 250 is one of many Flat Poly Bags available through Office Depot. Made by Office Depot.