This has been around for a long time. It is Rothstein's from Denmaks pedals. They make two. LOL
There main biz is making pre wired harnesses for
A toggle switch lets you switch between zener diodes for a very cool raunchy sound and silicon transistors for a smoother tube like sound.
I find it's the diodes that make for all the fun of this pedal. They make a great sound that keep it from being just another dirt pedal.