The "What Is This?" game

[Janx101]

Gee Menno... Showed up late and pinched the prize from the pass the parcel too!! Lol

First in best dressed as the saying goes...

You have it

Full picture..

[mennobike]

Another link, sorry!    the flash drive is for scale http://m.imgur.com/li0mD5z

[Elmojo]

Oh man, I was so close!
Oh well, I would never have guessed it anyway, since we don't have trains of any sort around here.

Menno, your thing looks like a bezel of some sort.
I was thinking split-ring keychain at first, but then I noticed the locking flanges.

I'm attaching the resized photo to save others the clicky clicky. 

[attachment deleted by admin]

[Janx101]

Bloody hellfire!! ... Another "I know I've seen one of those" moments.... 

[Janx101]

Vague memory saying... Engine or gearbox part.... crush washer?

[Elmojo]

Looks like it has lugs on the side facing the camera that fit into a hole with matching cutouts, then gets turned to lock into place.

@Menno: Is it metal or chromed plastic?

[mennobike]

Metal. Mojo is on the right track...

[Janx101]

Hrrrm. ... ok. . Lock ring for camera/action camera lens area?

[mennobike]

Very close, why isn't it attached to something?

[Janx101]

Because you needed to take a photo of it?? 

[Janx101]

Because it broke off?

[Janx101]

I'm tired and it's sleep time and I just can't think why the thingy is flying solo... unless it's the locking ring of a replaceable filter or faceplate of a waterproof housing? ... straw grasping here!

[mennobike]

Not for a filter or waterproofing, how about a hint?

It's threaded on the inside, and is never used with new lenses.

[pliskin]

Key ring

[Elmojo]

Lens adapter from one mount to another?

[mennobike]

Mojo takes it! M42 screw mount to standard Pentax converter.

[Janx101]

 

Legit! 

... And now I now where I saw it... Holidays last year when I was buying a polarised filter for camera! ... Sales/tech guy was fiddling with one on the bench...  ... I might have been drinking that day lol

[Elmojo]

Yay for me!
I'm stuck at work with no cool things to post.
Janx, do you have anything else to show? If so, please take my slot until I can get home to find something worthy of guessing.

[Janx101]

Ok.. I'm at work too but we on morning teabreak. .. try this!

[Elmojo]

Pressure sensor?
Flow meter?
I see abrasion on the pipes, which I can't imagine how that could happen.
Looks like electrical conduit though, so may not be fluid-related at all...