This is an optical compressor from Pigtronix, highly regarded for its high-quality pedals. - Model Name: Philosopher's Tone Micro - Brand: Pigtronix - Power: DC 9V center (-) - Controls: Volume, Sustain, Treble, Blend Unlike the "pacooon" type compressors like MXR, this is a natural and high-quality compressor. There are many demos on Youtube, so please take a look. There are a few minor scratches on the left and right sides of the unit, but it's generally in good condition. Original box and manual included. Instant purchase is OK. Thank you.