Ernie Ball Cobalt Extra Slinky Electric Guitar Strings (2725) gauges 8-38W come with an all-new innovative cobalt coating, wrapped around tin plated hex shaped steel core wire. Ernie Ball Extra Slinky 2725 guitar strings feature a stronger magnetic interaction between pickups and strings, which maximizes output and clarity and delivers a dynamic range way beyond that available with any other alloy. With the new Cobalt Extra Slinky electric guitar strings you'll experience incredible harmonic response, increased low end, and crisp, clear highs, as well as a soft and silky feel that makes string bending a breeze.