I just purchased and used the 263A with the stainless steel parts. Before it was the usual cheap pressure regulators and had to run around in the shower just to get wet. This solved all our problems. I have it set at 55 psi but at the last campground water pressure was only 45. It supplied enough flow to give us great showers.
All the connections needed come with it to attach to the faucet and hose. I'm happy with the price we paid. You won't regret buying this. I can't speak for all the others manufactures out there, I tried to put one together by buying the separate parts at Home Depot & Lowes but nobody had a pressure regulator for some reason. The few extra dollars I might of paid was well worth it.