On mine they pivot to the side off of the outside flapper/door. The pin that they pivot on is at the top of the two little levers. But then, my outside stove vent doesn't look like your picture.
There is also a sort of spring like thing inside the trailer, along the right side of the inside vent box (inside the hood but outside the grease trap) that needs to be pulled out to release the internal damper. Both need to open for the hood to operate properly.
I only mention this because some people don't know about the inside thingy.
Without adult supervision...
Quando omni flunkus, moritati.
I'm a man, but I can change, if I have to, I guess.