Since I don't have a clew as to its usage I figured this would be appropriate spot. What you see is all I've got. Whats it for ?
Wag , looks preload nuts. Maybe use a wrench on the flats? like it would work as a spanner on differential
What's it made from?? Colour looks like brass, or bronze, so could be a key for the flush fitting filler cap/waste water cover used on boat decks...
(http://www.downwindmarine.com/images/P/891330.jpg)
No just lighting. Cast iron or steel.