Product review (3 stars): Be advised, snow will get in!!!!!
Replaced plastic vent that was 1/2 as wide but the same length due to stained plastic cap and leaking.

After the first snow of the season, I noticed snow had blown between the vent base and the vent cap.  It began melting and leaking through the roof panels.(The problem this new vent was to resolve)

if the sides of the cap extended closer to the roof of the camper, this would prevent the snow fall from getting in.

Either that or plan on putting a cover over your cover!!!!