vintage maestro ring modulator. this is the last one i have to sell. came from a friend who used them in the 70s. this one has been modified with multiple AC outlets on the back. back in the 70s there were lots of effects that ran on AC so you had to plug them in. he had about 8 gadgets on his effects board so he installed these on this unit as it was the only one that had enough room in it. there is also a red LED looking light that comes on when the unit is switched in. these were made in the 70s i believe. unit powers up and functions as it should. switches and sliders function fine. one of the small plastic square sliders knobs is missing. volume slider increases level and the other two sliders change the sounds. the high low switch works fine and the modulate on off switch works. again since this is vintage its sold as is, but i hooked it up and it powers up fine and makes the ring modulator sound. a nice addition to your vintage pedal collection!! thx!