DR Strings BKB-50 Black Beauty Heavy Bass Strings Advanced black coating for EXTRA-Life and Protection Extra-Life Black Beauty strings offer bass players a superior black coated string without sacrificing the crisp tone, clarity, and volume of traditional DR handmade strings Extra-Life has a super thin advanced 0003" Black coating on the plain strings and on the wrap wire Extra-Life Black Beauty strings offer bass players a superior black coated string without sacrificing the crisp tone, clarity, and volume of traditional DR handmade strings