This is a simple metronome.
The only thing that's different from others is no click sound.
It beats the rhythm by vibration instead of click sound.
Let's play music instrument in the correct tempo, putting this app in your pocket.
If your smartphone doesn't vibrate, check your smartphone's vibration setting.
I think many Android devices have vibration setting in "Sound & Notification".
If vibration setting is off or "Silent mode" is on, please turn vibration setting on or "Silent mode" off.