When the Ukulele first appeared (circa 1874), gut strings were the only choice available. The gut strings initially used were those of the Violin (first and second string). Then in the '30s, appeared the specific Ukulele sets were made. After about 1938), Nylon became the string of choice because of its lower cost, longer lifespan and high stability to climate changes. However, many traditional musicians continue to prefer genuine gut strings for its playability and its ability to imitate the human voice, Aquila Genuine Gut Strings are made exactly with the same materials, and to the same specifications of gut strings from days of old.