New from Electro-Harmonix is the Double Muff, a dual Muff overdrive pedal so if one original Muff Fuzz circuit isn't enough, you can kick in a second for an all out fuzz assault.
In single mode, the amount of overdrive will lessen as you decrease the volume on your guitar. You can compensate for this by increasing the volume of the Single Muff. In Double Mode, the Muff knobs will interact with each other so that you can tweak your sound for the perfect amount of distortion.
The Double Muff can run on either a 9V battery or an external 9 Volt power supply.