Gauge 11-14-18-28-38-50. Pure Blues electric guitar strings from DR Strings are designed with pure nickel wrap wire roundwound upon round cores. While this is a slow expensive method of string making it does produce a guitar string acclaimed for increased sustain vintage tone and great low tones for playing music from rhythm to lead. The extra step of winding pure nickel around a round core give Pure Blues strings a punch that players say they are surprised to get in a vintage electric guitar string. Sounds great on any guitar!