Water pressure regulator valve?

Has anybody seen this type before? I believe it is a water pressure regulator valve. It is located just before the main water shut off valve on the exterior. It has a hose barb fitting underneath for some reason. On it is printed Watts Regulator No. 230, but I couldn’t find any info on it. Thanks you.

I think you are correct. Likely an older model than some of these. I did not look at them all.

http://media.wattswater.com/pg-prv.pdf

This looks like it.

http://www.watts.com/pages/_products_details.asp?pid=803

Thanks Michael and Kenneth.
It looks as if it acts as a adjustable pressure relief valve instead of a regulator then. Kind of similar. O.K. -----thanks

I’m curious about what it is for. Do you have any pics or info for the water heater?

i’m wondering if this is what you would use in conjunction with a Watts 210 valve?

Electric water heater.
This house was re-plumbed 3 years ago from PB to Pex, so this was recently installed. At the time I was just wondering if this was some kind of pressure regulator valve or something else but pressure regulator valves are usually in line with pipe and this is off of a tee. It has a dial on it to set the psi. Maybe if the pressure gets to high in the cold water supply it spits some water out to get to desired psi on dial. I don’t know.