The Ernie Ball Slinky 5 String Bass Guitar Strings are made from nickel plated steel wrapped around a hex shaped steel core wire, they produce a bright and balanced tone and are manufactured with the finest and freshest raw materials. Their signature recipe consists of specific gauges and core to wrap ratios for balanced, rich harmonics and that signature slinky feel. They're made by Ernie Ball in their California factory using state of the art winding technology for consistency and reliability. The slinky bass strings are packaged in their watertight element shield packaging to resist humidity and keep your strings factory fresh.