Yep, water pressure regulator. Far as I know, all the Luhrs Group companies used Jabsco units.
The original regulator in ours was a 35-PSI unit, semi-anemic and we have PEX plumbing... so more pressure seemed doable. Jabsco's more recent 45-PSI unit does work better, although I had to enlarge the cut-out a bit.
South River, Chesapeake Bay