Gauges 09-16-23-30. D'Addario J63 Tenor Banjo Strings are the choice of many professional bluegrass musicians. Top-quality plain steel and nickel-plated steel wound strings. D'Addario is the world's largest manufacturer of musical instrument strings. Many top guitarists won't play any brand other than D'Addario. Regardless of your playing style, D'Addario has a set of strings that's right for you.