This set is all Nylgut. Aquila New Nylgut Ukulele Strings have become the industry standard quality ukulele string set. In comparison to Nylon, New Nylgut sounds better, and holds its tuning better, as well as offering improved intonation. This because the moisture absorption is less of .1% against the 2.0% of Nylon normally employed for the musical strings. Due to the higher density, similar to that of pure gut (1.30 gr/cm3), the New Nylgut produces a better sound than Nylon and it is not so metallic like those of the so- called 'Carbon' (Fluorocarbon) PVDF strings. Although Aquila’s employees can provide some information on product characteristics, it is the Customer who is responsible for choosing the right items, in compliance with the specifications set by each manufacturer and according to his/her own personal requirements.