What is it?

Where did it come from? (or, what are you doing that requires it?)

Does it look like a mass produced item or a custom made "one off"?

I have no clue what to call it

Sounds custom-made.

Best you post some pictures for clarification. What's it for?

Strictly curiosity. Found it in my front yard. Don't know where it came from. There are 3 kids here, 3 next door and 3-5 who come to visit the cul-de-sac daily, so it could have come from anywhere.

It's definitely machined, I'd guess in quantity.

Guess I'll take a picture.

Note the self tapping feature in the first picture.

That's it. The middle one in the right hand group.

Nice job, I still don't know where they are used, except for attachment.

Clever, whatever it does.

Cheers.

It's an anchor for hanging light loads from 3/8" rod to be screwed into wood. Allows the ease of use of most industry standard hangers made for 3/8 all thread.

We use them for hanging conduit, piping and fixtures from roof and ceiling joists. The threaded rod goes into on of the threaded holes in the head after the other end is screwed into the wood. Or that is what the construction industry in my area uses them for.

Seems logical to me.

Looks like a specialised version of a "Tek Screw".

Tek screws come in different styles to suit the application, usually they're used to screw roofing iron to purlins. But theyre (ab)used in other ways because they're machine fitted with either a power drill or specialised power driver

http://selftappingscrews.org/tek-screws-specifications

http://www.efl.bz/pdfs/datasheets/tekmetalframedatasheet.pdf

http://en.wikipedia.org/wiki/Screw

http://www.grade1fasteners.com.au/Online-Product-Catalogue/Hitachi/Power-Tools/Hitachi-Power-Tools/Hitachi-8mm-Tek-Screw-Driver-Model-W8VB2.html

Now Ive either given you an answer or led you up the garden path...

None of the above, but it was a nice walk.

The visible male threads look like wood screw threads, for going into wood joists/beams. The other end looks like female machine screw threads, for extending all-threaded rod to pipe or fixture supports, or whatever. These are sometimes called "rod hangers."

Yep. Somehow, I've never seen one of these till today. This one's 3/8" female.

Among other uses: for easily fitting, and, removing table legs.

It is a lock puller made to use with a slide hammer to open safety deposit boxes.