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!