D'Addario J92 Pro-Arte Ukulele Strings, Concert Optimized for Concert Ukuleles tuned to standard GCEA tuning Nylons made from the renowned D'Addario Pro-Arte series with highly accurate, laser sorted treble strings Inspired and guided by DAddario ukulele artist Jake Shimabukuro Made in the U.S.A. for the highest quality and performance String Gauges: Nylon .028, .032, .0403, .0280