Kala brand tuner super simple and practical. It has a clip to put it on your Ukulele and with a single button you can select the instrument: Guitar, Ukulele, Bass, Violin. Just put it on the Ukulele and you will see that when you mark green on each of the strings it is ready! In less than a minute you already tuned it. It comes with a fairly durable clock-type battery, and in any case, easy to get. A Classic Ukulele Tuner.