This is a used SR&D ROCKMAN ACOUSTIC GUITAR PEDAL unit and adapter. I didn't notice any particular problems with this combination, and there were changes in tone depending on the knobs, but please note that I haven't confirmed the details. It's an acoustic guitar simulator, but since it seems to be based on the ROCKMAN CLN2, it might also be usable as an alternative to the clean Rockman sound. The pedal's gray color and the adapter specifications and rear panel specifications suggest that it's an SR&D version. It basically worked with the included Jim Dunlop 12V center-positive adapter. When I opened the back cover, there was a place to connect two 9V batteries, and I confirmed that it worked with them as well. However, I got the impression that the batteries didn't last very long.