Our 12 x 18 4Mil Flat Poly Bags on a Roll All our clear Layflat Poly bags on a roll are made of 100% virgin Low Density Polyethylene (LDPE) resin that meets FDA/USDA specifications. Easy dispensing with perforations between bags. Tubular construction with a durable double bottom seal makes these the best on the market. This premium bag features superior clarity for showing the quality of your customer's product. Neatly wound on a 3" core with 1" diameter core plug. Can be heat sealed, tied, stapled or taped shut.