This is a lightly used BBE OPTO STOMP, optical compressor.

Well known for it's transparency, the BBE OPTO provides a very clean and simple to control compression commonly used with Guitar, Bass guitar and other instruments. This unit is lightly used with a few small paint chips, it was used in my own recording (fully tested) with no missing or broken pieces. This OPTO operates on 9v battery or 9vdc (center -) standard effects adapter (adapter not included).