This is a morphing crossfader. It is a proportional signal mixer.
It is done with the help of the central sliding potentiometer.

You will get very interesting tones with VCO signals. You can also morph CV signals for total madness !

You can plug 2 signals a the top and 2 others at the bottom.
Signal 1 and 2 are mixed 50/50. The same goes for 3 and 4.
With the sliding potentiometer at the top you get 100 % of the top signals and 0 % of the bottom ones.
With the Potentiometer at the bottom it’s inverted.
With the potentiometer at the middle position you get a 50/50 blend.
Of course, you can get everything in between proportionally with the potentiometer position.
The buttons allow you to cut or pass the signals of the corresponding input jacks.
The LED is on when the signal can pass.
The volume knob is controlling the final output volume.