Ernie Ball 12-String Medium Nickel Wound strings for electric guitar feature a wound G string and are commonly referred to as jazz strings, although they are by no means limited to this genre. These strings are precision-crafted to the highest standards and specifications, ensuring durability, optimal performance, and longevity. All wound strings have a nickel-plated steel winding on a hexagonal steel core. The plain strings are made from specially hardened tin-plated carbon steel, providing a balanced tone.