Nice looking black strings, I used them on a concert ukulele. They have a smooth feel and a nice mellow tone. These strings are not as loud as the other popular nylgut strings.
My main problem was the really bad intonation, especially on the C string, even the D on the second fret was way off. Of course this could have been solved by making a new compensated saddle for this string set if someone really likes this mellow tone.