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.

I wonder if the two tangs at 9 o'clock are the remnants of the hinge. The lid / door is missing of course. I can imagine the teeth a noon and 6 o'clock are the index for a bail or bar on the underside of the missing lid, that would give the operator an option of different levels of openings, like the different ridges in walls of your oven let you move the rack closer to or further from the heat.

Not an exact comparison...

The pair of teeth closest to the hinge would be the widest partial opening, then click click click click, lower and lower as the support bar moves farther from the hinge.