Welcome to the forum.
I don't know what kind are on your RV, but it really doesn't make much difference. There are several different brands that will fit in the same space, and are considered interchangeable.
Before you replace the vent, are you really certain that the vent itself is leaking? Much more likely, is the seal where the vent meets the roof is leaking. That is easily repaired without replacing the vent.
As for being brittle, I am not sure I understand. The vents are rigid plastic, and are always somewhat brittle. Are you referring to something other than the body of the vent?
2011 Silverado 2500HD Duramax, 4x4, crew cab, long bed
Palomino Puma 253-FBS, 27' 5th wheel
1994 19' Class B on Chevy chassis