These White Block Clearzip plastic zip lock bags are perfect for labeling custom orders, indicating manufacturing dates, assembly instructions or warnings, as well as labeling lightweight parts and samples. The Ziploc bag's white-block area allows for you to write on the ziplock bags and they accepts marker, rubber stamp, grease pencil, or pen. The side-welded zipper top whiteblock bag seal reinforces the bags zipper for added strength and insures these Ziploc whiteblock bags are resealable and reusable, no matter how many times the bag is opened and closed. All whiteblock Clearzip plastic zipper bags meet FDA/USDA specifications for food contact. International Plastics the leading provider of wholesale ziplock plastic bags with White Block writing area.