Gay-Milano tracking voltmeter

I acquired this digital voltmeter through a swap deal with a fellow hobbyist. It is a nice compact digital voltmeter using 4 small nixies for display.
This Italian DVM is built very compactly. It has four ranges, selected by push buttons:
- 1, 10, 100 and 1000 V
I acquired this digital voltmeter through a swap deal with a fellow hobbyist. No manual came with it. Unfortunately, the mains cord didn't come with it, either. As it has a very non-standard mains receptacle, I wasn't able to hook it up and test it yet.