What is this?
 

Man this is familiar but I can't figure it out. It was in an old burned out cabin. Heavy like a stove part...

Mebbe the smoke dampener for the stove.

Pan for an electric meter?

Looks like a door would hang off of those hinge tabs on the left there. That means the thing is in its correct orientation, or is upside down. I think it's in its correct orientation, and a stove pipe type piece fits in the round lip. I have no idea what those notches are inside the circle. I'd guess some sort of notches to hold a damper in place at different settings.

I really am grasping here though. No idea.

If it's a damper and usually closed at night when the fire is banked, the notches may be so the flow can't be choked off entirely. Banked fires make CO too.

hmmm... maybe
Cast iron so I don't think so.

This was near an abandoned ski lift as well so it could be something related. Old junk 50s era pickup nearby as well.

Spexx!

Hi Spexx.

Hey l:eyeball::eyeball:k! It's Spexx!

Hi Spexx! Right material, so likely a stove part.

Is that a box on the left side? Or a vent?

Vent

There are things called damper (in round pipe) to duct (square or rectangular vent) adapters that look a lot like that.

I think that's it. I'm not sure about the function of the teeth. It looks like you could rotate the pipe but maybe it's just a clever dampener.