Nathan's® Coney Island Natural Casing Beef Frankfurters. Gluten free. No artificial flavors or colors. No by-products. Since 1916. Famous. The original. Nathan's. Famous. Frankfurters. U.S. Inspected and passed by Department of Agriculture. Under license from Nathan's Famous Systems, Inc. To retain original Nathan's flavor we suggest grilling. With Natural Sheep Casing to help seal in flavor. www.nathansfamous.com.