Cool bar lamp-Need help.

So I'm perusing etsy when I find Zal Creations. This guy/artist is a genius. I'm thinking about making something kind of similar, but I'm not sure how one of the pieces works. Does anyone know what the piece that holds the beer bottle to the lamp is called?

Looks like the female end of a union. But honestly he's probably not using it to hold the bottle. I doubt a bottle would screw into that. I bet he has it glued in.

Could you email him and ask?

The hexagonal part of the piece screws off. I'm sure he uses a washer or a grommet of some sort to keep the bottle in (it has to come out to allow the light bulb to be changed). I've just never seen a pipe fitting like that. With all of the HVAC/Engineer/Smart People on this website, I was hoping somebody could tell me what the piece is called so I could search for one.

Regardless, I still think I'm going to build something like this.

Does the valve actually power the light on or off?

Looks like he may be using a Galvanized Male Compression Adapter.
http://www.plumbingsupply.com/galvanized-compression-fittings.html

It is half of a brass compression fitting. You should be able to find one at any big box store.