Ok here are a description of several water pressure regulators and a comment.
one of the CG's I stay at when they hand you the campground info sheet/map it mentions the measured water pressure is in excess of 120 PSI (city water) Believe it. I've confirmed. this kind of pressure can blow the end off your hose and did blow up my Fresh water hose.. kind of like the cartoons where the character blocks the water flow and the hose gets bigger and bitter and KABOOM only not qute that impressive (Shot a stream not a flood)
Next page.
Small 3/4" cylinders, brass or plastic male hose end on one end, female on the other.... JUNK these restrict flow. OK for washing dishes but not for a shower.
HIGH FLOW. Like above but often have a bright Plastic-rubber grip on the female end (Camco puts Wings on the body of the plastic one) Better for washing dishes, Still not too restrictive.
Valterra adjustable (About 20-30 bucks) I have not yet tried one of these. but........ Others report good results with them.
Now I have a Watts 3/4 inch that needs a rebuld. and a ZURIN 3/4 Inch that is all but new. about 60 bucks each.
WHen I hooked up the ZURIN I put a pressure gauge on it and set the pressure (Static) at 50 PSI, then I turned on the shower and watched the needle on the gage.. NOT MOVE AT ALL.
When the Watts was new it did the same thing. but as they age.. Well they start to fail to fully open.. I'll get a kit and rebuild the Watts. and re-test it.
kits are not expensive and the job is easy.
These units have an "upper" hosuing that is bell shaped. the pressure adjustment is the bolt that would NORMALLY hold the bell to the yoke or handle. if it were a real bell