Ernie Ball 12-String Electric Strings. Ernie Ball 12-String Slinky Strings are the perfect set for your 12 string guitar! 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. Ernie Ball 12 String 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.