We bought this vent at Camping World outside of Portland and have been driving around with it sitting in its box since then.  Its a drop-in replacement for the vent the bathroom which also the only manual roof vent in the motorhome. There used to be a fantastic vent with a built-in fan in our motorhome (there are manuals for it), but for some reason it had been replaced over the years with a crappy non-fan one. Because there had been one in the past though the install was super easy as the wiring was already available in the ceiling and these things just drop right in to the 14"x14" vent hole which is standard on all motorhomes.

While I was up there I slathered some Dicor Lap Sealant on a bunch of spots we think could leak and I spent about two hours cleaning regular house caulk on top of tree-sap on top of old sealant that was all around the skylight in our shower. I was able to clean it all up back to the original, still maleable sealant, and with the fresh coating that sylight seems to be water tight. It rained a few hours later, so hopefully that didn't mess anything up. Nothing leaked though!