Made of 100% virgin Low-Density Polyethylene (LDPE) resin, which meets all USDA and FDA requirements for food contact. We offer over 1,000 sizes of flat poly bags in stock and same-day shipping! Lay flat bags are available in a variety of thicknesses (mil) with unique uses and advantages ranging from 1 mil to 6 mil. The mil refers to the gauge or thickness of the poly bag. For instance, a 1 mil bag is fine for packing a sandwich for lunch, while a 6 mil bag will contain sharp objects like nails or jagged rocks.