Electro-Harmonix Nano Muff Overdrive Pedal Small die-cast case saves valuable pedal board space No complicated settings needed here: just the switch and a volume knob Rugged construction and amazingly compactto save valuable pedal board space! The red LED indicates when the effect pedal is switched on You can power the Nano Muff Overdrive pedal with a 9V battery, or an optional 9V 100ma tip-positive AC adapter with an 1/8" plug