Our 4 x 20 4Mil Flat Poly Bags Each of our Imported Layflat poly bags are made of 100% virgin Low Density Polyethylene (LDPE) resin that meets FDA/USDA specifications. Manufactured with a durable bottom seal for optimal strength. This premium bag features superior clarity for showing the quality of your customer's products. All listed gauges are nominal. 100 Packed. Can be heat sealed, tied, stapled or taped shut.