Ernie Ball RPS Nickel Wound electric guitar strings feature plain strings (E, B, G) with a patented winding of brass wire that is tightly wrapped around the lock twist of the ball-end. RPS strings last longer and stay in tune better than conventional plain strings. Wound strings are made from nickel-plated steel wire wrapped around tin-plated hex-shaped steel core wire. Enjoy world-renowned Slinky electric guitar strings with enhanced strength. Gauges .008, .011, .014, .022w, .030, .038.