What is this and what does it do???

[Wingeezer]

Some sort of mechanical doorbell, seized up and missing the outside twist knob?

If not, then I give!

Maybe taking it apart will give more clues.


Brian.

[mhilley]

I know exactly what it is. It is an adjustable flux capacitor. I know because I have one. When you come into the trailer and remove your tin anti flux skull cap you adjust the nut until the hum goes away. That's one advantage of an tin trailer - it keeps the random flux radio waves out.

[AStreamNerds]

Could it be some sort of tie point for a bungee cord to hold the door open or closed? The hardware could of been laying around the previous owners garage and they had a light bulb moment and drilled the hole.

[msimon]

Gotta be a place to attach a dog tether.

[Piggy Bank]

Here's my imaginative idea. Say it is a dog tie-out tether bracket. Say that you could install a doggie door on the bottom half of the screen door. Say that you would have a double clip leash. Have the leash clipped onto the tether-bracket. Open the main door. Have other end of leash on Fido. Now Fido may go in or our without disturbing you as you sit and enjoy your evening beverage by the fire.

Yes I am clearly just making this up.