DR Strings BKE-9 Black Beauties K3 Coated Guitar Strings 9-42DR Strings, makers of the world's finest handmade guitar strings, combine the latest wire technology with old fashioned craftsmanship. The costly wrap wire is the latest in coated technology. The wire is pre coated before winding for extra life and extra protection. This coating includes a corrosion inhibitor for extra protection against damaging substances such as perspiration, dirt, humidity, and "acid hands". DR Strings offer players a superior