Mine is equipped with the famous Red Fasel. Technologically it's vintage, input, output, plug adapter, and an old switch activated when you arrive at an end.
It is a volume pedal / wah.
Next volume, the sound is not muted when you are at a minimum. Therefore not ideal for a violoning effect. On the other hand it allows to vary the gain gradually saturated the channel of the amp.
The switch is sensitive enough that you easily switch the mode volume wha-wha and vice versa.
In volume mode, the pedal seems to provide additional gain when it is fully. For my part, I use a lot of distortion channel of my amp, at least I have a slight crunch for rhythm and a good maximum distortion for solos, but the volume is too affected to an extreme to the next race.
Mode wha is fat and warm, vintage at will, the swept frequency range is just for the funk, but perfect for blues / rock. Personally I love it!
Especially since despite his advanced age it does not spit his lungs with each manipulation.
I bought it used, and I rediscovered every time with great pleasure. I was looking for a simple wha, but finally I use the volume function frequently.
It has a fairly high side but worth it.