Ernie Ball 2737EB Super Cobalt Slinky Electric Bass 5-Strings 40-125Ernie Balls most popular string gauges are now available for Cobalt Slinky and Cobalt Slinky Bass sets. Gauges include Ultra, Burly, Mammoth, and Primo Slinky for guitar as well as 5 and 6 string sets for bass. All Cobalt Slinky and Cobalt Slinky Bass strings feature a patented cobalt wrap wire around tinplated hex cores for enhanced output and clarity. Features Engineered for maximum output and clarity Precision wound with iron cobalt wrap wire