said, there are many references to VENT CAP.
There are plumbing vent caps and
Camco 40034 RV Polar White Replace All Plumbing Vent Cap Only.
Replaces the lost RV plumbing top cap,
Separate cap fits up to a 2 inch pipe,
Features spring tension attachment, which eliminates the need to replace the entire vent,
Easy to replace. Remove the damaged cap and install the new, spring loaded cap.
And, there are Vent Lid (Cap).
Which is also easy to replace.
Crank the lid to the full open position. Remove the inside crank handle(Phillips Screwdriver), remove the inside insect screen. remove the two crank gearbox retaining screws and slide the raising arm out of the slot.
Go on the roof and bend the hinge cover retaining tabs and slide the damaged lid off.