Ernie Ball Slinky Nickel Wound electric guitar strings are their top selling string and are the choice of many pro musicians around the world. They are carefully made to meet high standards and specifications in order to maintain consistent performance and string life. Regular Slinkys are made with a nickel-plated steel wrap wire wound on a hexagonal tinned steel core. Slinky plain strings are made from special tinned high carbon steel and help produce a balanced tone on any guitar. RPS Slinky sets have reinforced plain steel strings.