I'm the original owner of this Demeter Opto Compulator, purchased new in 2005. It's in very good clean 'n' quiet condition - volume and compression pots are not scratchy nor noisy; footswitch is quiet. Cosmetically, it's near-pristine, save for the remnants of some silicone adhesive on the underside previously used to attach a small strip of Duralock. Ships in its original box. No power supply included, but it has a fresh 9-volt battery. $110 shipped to the lower 48. PayPal or money order. Not interested in trades. Thanks for looking! Here's what the manufacturer says: "The sound of classic studio optical compression of the 60's and 70's at your feet! The first compressor pedal not to suck the life out of your tone. Operation is fairly straightforward. There are two inputs on the front side of the unit: a 1/4" input jack on the right and a 1/4" output jack on the left with a battery-ground switch on the input jack. There are two controls on the unit: compress and volume, plus a foot switch to bypass the effect, and an LED to indicate effect operation. On the side there is a trim pot to set the overall gain of the unit. Compress affects the amount of gain reduction (compression) of the input signal. Turning this clock wise will give you up to 30dB of gain reduction (depending on input gain). Please note that the Compulators max gain is 26dB (see Trim Pot) so in some circumstances if your instrument is very hot you could achieve less than unity gain if you turn up the compress knob too much. Volume increases and decreases the output volume of the Compulator. Use this for level matching between the effected and unaffected signal. Trim pot sets the gain of the compressor's pre-amplifier. If distortion occurs turn this down until the signal is clean. The unit is set at the factory at 20dB of gain which is perfect for most instruments. If you have weaker pickups or want to push the envelope turn it up to its max gain 26dB. Power supply: 9 volts DC. Either external or internal. For internal power, use a 9 volt battery. To access, remove the four screws on the sides of the unit and pull apart. Note: battery must have at least 7 volts for unit to work! External power supply using mini plug, tip positive, 9 volt DC regulated (100 milliamp or more)."