There are pressure regulators and there are PRESSURE REGULATORS!!!
Now the "Standard" regulator marketed to RVers is a cylinder, about 3/4" in diamater, female hose on one end, male is actually the body. JUNK
THe High FLow, is like the above with either wings or a bright plastic grip on the female end.. like the above JUNK
Sur-Flo markets an IN-Ine.. it is identical to the bult in regulator on high end RVs only with a screw on male hose adapter on the outlet port.. I give it a 9 when new. (NOT JUNK)
Valterra makes an adjustable unit, NOT a cylinder like the standared RV uints. I have not tested it but others speak highly of it.
Watts (Makers of Sur-Flo) and Zurin both make a line of regulators. These hafe a bell shaped upper housing with a bolt in the midde of it (Pressure adjustment) where a standard bell would attach to the handle or cradle.
You also need a pressure gauge. a Y and hose adapters.
OH, new they are 10s. Solid 10s. as they age however they 9-8-7-6 but you can rebuild them and back to 10.