Ernie Ball Extra Slinky Electric Strings are widely revered for their world-class tone. These strings are precision manufactured to the highest standards and most exacting specifications to ensure consistency, optimum performance, and long life. Extra Slinky wound strings are made from nickel plated steel wire wrapped around a hex shaped steel core wire. The plain strings are made of specially tempered tin plated high carbon steel; producing a well-balanced tone for your guitar.