NIckel-plated steel on traditional roundcore;Significantly less tension, better flexibility and more sustain than hexcore strings with hexagonal core ;Optimal sound, easy to play, long sustain ;Roundcore strings must not be shortened before tensioning, otherwise the wrapping could come loose and the string becomes unusable. ;X50XL Nickel Explosion .009-.042 extra-light;Extra-Light .009 .011 .016 .024w .032w .042w;No single strings available!;