Simple and practical Kala sper tuner. It has a clip to put it in your Ukulele and with a single button you can select the instrument: Guitar, Ukulele, Bass, Violin. Just put it on Ukulele and you will see that when it marks green on each of the strings it is ready! In less than a minute you already tuned it. It comes with its fairly durable watch battery, and in any case, easy to get.