Fuzz and some other pedals sounds really good when the battery dies.
This small tool simulates this effect.
Plug your regular 9V power supply into the dying battery simulator and you can regulate the current from 0-9V with the potentiometer.
-made in Germany
-Simulates a dying battery
-Current regulation from 0-9v
-For 9V power supplies/ centre negative
-9V in- and output