The Volume Preset pedal is used to switch between a bypassed volume and a preset lower level. The knob works just like the volume knob on your guitar.
This is great for presetting a lower volume, for example for rhythm playing, and switching to your bypass level for lead parts or overdriving your amp.
When powered the Red LED is lit when the signal is muted.
This pedal is completely passive and needs no power to operate. The only power needed is for the LED