Wha wha pedal switch using a switch or whawha alone or whawha + fuzz.
The filter is controlled via a knob that rotates via a gear rack +.
No optical system.

UTILIZATION

I bought new in 1971! She never dropped except the switch that I replaced in 2006! Even the knob is original.
Only regret, no power jack.
But as I head up in the cascade effect, and the signal to noise ratio depends on the first element of the chain, being battery powered, guaranteed
a lack of hum and thus optimum signal to noise ratio.

SOUND QUALITY

Wha position without fuzz, it can sound very funky.
Followed by a tube distortion Français muff'n the sound becomes grandiose.
Hendrixien, Ledzepien, ACDCdien etc ... and this on a Twin reverb!
I utillise as well with a Start / Super Start or Gibson.

Fuzz position, the sound is interesting, but lacks punch.
Fuzz for a good sound, I set the gain Français muff'n with minimum or
9 am and the sound is less grim Fuzz and style "
Satsifaction "Stones.

Preque position at the top, it sounds very Black Sabath

OVERALL OPINION

What about ... after more than 35 years of good and loyal service! I strive ....
It does its job and have never tried anything else.