The dial range is from 0 - 50.
I can't really think of anything that ideally falls into such a range (not a combination lock, and probably not a camera thing either).
The large center hole could be for a potentiometer (i.e., a variable resistor), such as a volume control, or similar electronic adjustment.
And speaking of electronics, many area of the world use 50-Hz power - not that that much here.
Also, just wondering, what kind of head is on the screws (hex, pan head, etc..), and are those wood screws (my guess), or might they be machine screws.
If they are wood screws, that might narrow down the possibilities....?