20" x 20" - 1 Mil Flat Poly Bags. Economical light-weight Poly Bags protect products from dirt, dust and moisture. Bags are manufactured from 100% virgin, high clarity polyethylene film. Meets FDA and USDA specifications. Close bags with twist ties, bag tape or by heat sealing. Available in case quantities. 500/Case.SHPPB2420. PB2420. Shoplet select Shoplet select 1 Mil Flat Poly Bags.