Aquila 59U Bionylon concert ukulele strings are tuned in the standard key of C, and offer the warm and mellow sound that ukulele aficionados traditionally enjoy. The plant-based Bionylon they’re made from boasts much lower moisture absorption rates (less than 0.1%) than synthetic nylon (2%), which significantly improves the stability of these Aquila ukulele strings in humid conditions. In addition, Aquila Bionylon is touted as “the world’s first eco-friendly synthetic string” — the manufacture of this castor oil-derived polymer emits 50% less carbon dioxide into the atmosphere than the production of regular, fully synthetic nylon strings does.

It’s easy to restring your concert uke with the Aquila Bionylon 59U. These pearl-colored strings are marked as follows (treble to bass):

n 1st A (red)
n 2nd E (blue)
n 3rd C (green)
n 4th G (white)