Martin M600 strings came standard on my Martin ukulele. I like the loud bright sound and bought a new set when the originals wore out. These are thinner and feel softer than the nylon Aquila strings that many people like. I think the Martin fluorocarbon strings give me more detail and just as much volume as the Aquilas. The Martin strings also break in faster. In less than a week, I only have to tune them once a day (compared to 3 weeks to break in Aquilas). Martins are also cheaper than Aquilas.