●The information below is per-pack only ●Ernie Ball Slinkys are played by legends around the world including Jimmy Page, Metallica, Eric Clapton, Slash, and more ●RPS Slinkys feature a patented winding of brass wire tightly wrapped around the lock twist of the ball-end of the plain strings (E, B, and G) ●Minimize slippage and breakage at the ball-end of the string ●Wound strings (D, A, and low E) are made from nickel-plated steel wire wrapped around tin-plated hex-shaped steel core wire ●Made in California, USA with the finest and freshest materials