I just put a Maxx Air cover over the electric fan vent in the bathroom in our 2013 Eagle 284BHS. IIRC, Ventline was the manufacturer of the vent. I took my time making sure I measured twice and drilled once. But it went on without a hitch. The only thing I might pass along is to make sure you adjust the forward/aft position of the Maxx Air vent cover (before marking and drilling the screw holes) to ensure the vent lid can be opened to the maximum amount possible before contacting the underside of the Max Air cover.
FAA A&P mechanic, ex-RV dealer parts dept
Retired B-52 Gunner/Flight Examiner, B-52 Crew Chief
2016 Jayco Eagle HT 29.5 FBDS w/ 15,000 BTU AC, 50 amp service, upgraded counter top, thermal pane windows, elec. stab jacks, outside grill, backup camera and MORryde pin box.
2011 GMC 2500HD DURAMAX/ ALLISON