Nickel plated steel electric. The Silencer process of “Inverse String Winding” compresses the outermost part of the cover wrap leaving the internal portion of the string intact. This design gives a bright sound with a semi-flat feel. Gauge: Light .011, .015, .020SL, .026SL, .036SL, .050SL Package: 6 Strings S.I.T. (“Stay In Tune”)… It is our goal that you will always be in tune if you are using any of our products. S.I.T. Strings was founded on a belief that a guitar string is more than just an accessory of little importance, but rather an integral part of a musician’s sound and voice. That is why, since 1980, we have been manufacturing strings one at a time, all here at the S.I.T. Strings factory in Akron, Ohio USA.