Here’s what Electro Harmonix says about the Rams Head Big Muff:

The EHX Ram’s Head Big Muff Pi delivers the unmistakable articulate string separation and exceptional sustain that’s made the V2 Big Muff so sought after. Now with a few choice updates for convenience including true bypass switching, an LED to indicate effect status and the option of being powered by a 9-volt AC adapter.

This pedal is used and in excellent condition. Pedal has been tested and is fully functional.