D'Addario J54 Ukulele Strings, Tenor Ukulele/Hawaiian Optimized for Tenor Ukuleles tuned to standard GCEA tuning Black precision rectified nylon ensuring that the roundness and dimension control of each string are unsurpassed Preferred for their warm and long lasting tone Tenor Ukulele, Black Nylon, Aluminum Wound, Non-Ball End Made in the U.S.A. for the highest quality and performance