It's an ENO BMF fuzz.
the tone knob is indeed labeled "SUSTAIN" and the fuzz knob "TONE", as is already known about this pedal.
It has lots of gain, too much even with the middle knob in that position, I back it a bit from how it is in the picture.
It seems to be some kind of Sovtek copy I would say, I don't know if "Civil War" or green Russian, but it seems some of the "Civil War" Muffs had the green circuit, the earlier ones having the Red Army Overdrive circuit.
I don't know if I recommend it, I couldn't get it to sound better than this:
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but I could easily make it sound worse. On the other hand, I don't have a mids control on my amp and if I turned the tone up on the fuff it got too mid-rangey; it was at around 11 o'clock.
Maybe I'm not into Muff fuzzes. I tried a Sovtek "Civil War" brand new in a shop in the 90s, liked it, but I had different tastes back then. Also tried someone's original 1970s USA, I borrowed it long enough to know I don't like it.
More recently I tried a Mojo Hand fx Colossus in a shop, not with my gear of course, I kind of thought it wasn't that good for 150 €, but also I was kind of pissed off they changed the graphics and it looks kind of stupid. I know it doesn't matter that much, but for that price I would rather have it look cool.
On the other hand, I like the Eno metal distortion a lot, you can get much fuller sounds, you can even get it somewhat fuzz sounding, much more versatile.
(she/they)