This is a parametric equalizer that also can serve as a very versatile boost pedal.It has two frequency bands you can choose between: low (about 40-400 Hz) and high (about 300-3000 Hz). The boost/cut is +/- 15 dB. A JFET output gain stage adds an extra 26 dB boost. Works with 9-18V DC.
You might call it a semi-parametric eq, since the “Q factor” isn’t adjustable. The Q factor controls the bandwidth that will be cut or boosted. The lower the Q factor, the wider the bandwidth. A higher Q factor means narrower bandwidth. In this pedal Q depends on the boost/cut. At max boost/cut (15 dB), Q is a little more than 1.5. At 9 dB boost/cut, Q is a little over 0.8. Boosting and cutting frequencies using a Q in the area of 0.6 to 1.0 is considered sounding “good”.
You can scoop out your distortion for a chunky palm muted tone, or boost the mids for a honky sounding solo. Or use it as a clean boost with maybe some boosted high mids to push your amp.
The controls are: volume (level out), cut/boost (adjust between -15 and +15 dB, noon is no cut or boost), frequency band switch (switch between 40.400 Hz and 300-3000 Hz bands), and frequency (adjust the frequency in the chosen frequency band).
Here it is, used as a tone shaper after a fuzz: