ceiling vent on the roof

I was washing the roof yesterday and noticed the cover missing on the attic vent in front of the skylite over the shower of our 2009 BC 3500RL.

Its not a plumbing vent, Its the attic vent and it has a nut holding a cover over a screened part

About 4 in in diameter.

Who makes it and is it available at dealers.

Laurent, call HL with your VIN#. I bet they have one.

Thanks