Pressure regulator?

That is a log style regulator, Moroso used to make them. The pressure is controlled by washers that are inserted into the tube. Personally, I think they are a POS, a friend had one on his race car and it was constantly contaminating the oil with gas. He is lucky he didn't explode the oil pan with as much gas as he had in the oil. I would change it to a screw/locknut style regulator.