Ernie Ball Power Slinky Cobalt Electric Guitar Strings - 11-48 Gauge. Engineered to maximize output and clarity, Ernie Ball Cobalt Slinky Guitar Strings are the latest innovation in string technology. Seeking to provide guitarists with a new voice, cobalt strings provide an extended dynamic range, incredible harmonic response, increased low end, and crisp, clear highs. Cobalt provides a stronger magnetic relationship between pickups and strings than any other alloy previously available. Cobalt Slinkys are also soft and silky to the touch, making string bending a breeze.