Metronome - Tempo, developed by KHTSXR, is a free Android app that produces regular, metrical ticks to help musicians or composers keep a steady tempo while playing or working on irregular timing and tempo. This app can be set to variable beats per minute (BPM, tempi) and is suitable for musicians of all levels.

The app is incredibly easy to use, with a simple interface that allows users to adjust the BPM to their desired tempo easily. However, it's worth noting that the app may not work well for tempos above 208 BPM. The app works perfectly for tempos ranging from 40 to 208 BPM.

Overall, Metronome - Tempo is an essential tool for any musician who wants to improve their timing and tempo. It's a great app that functions well and is available for free.