4 mil Clear Line Single Track Seal Top Bags with Write-On Block LK Packaging's Clear Line Seal Top Reclosable bags feature a white write-on block so you can easily identify the bag contents. Use it to record date, lot number or other important information. The zipper type seal closes securely and is easy to open and close time after time. These bags are excellent for storing, displaying, protecting and shipping all types of product. Because they are made only with virgin resin, they meet FDA requirements for contact with food products.