Shield N Seal’s Clear and Black Vacuum Sealer Bags are perfect for long term storage of food and perishables. These bags are the thickest, BPA free, food grade heat seal rolls. Studies have shown that properly vacuum sealed food can stay fresh up to 5x longer, sometimes 10x longer. Clear and Black construction allows for supreme versatility.  Some times people like to be able to see their food through the clear side, and other times, it is better to have your bags be light proof.  To protect from light and sun, simply double bag, flipping one bag around. Viola, light proof and double bagged!