4″ BLACK Plastic Round Rotaire Grille Heat Covered Screws Outlet Vent 3940BK RV Trailer
Two piece snap together design covers the 2 screw heads.
360 rotation, easy installation and long term durability.  Accepts 4″ flex duct.
See tape measure pictures.
Approximate size:
Grille face diameter 5 1/2″
Back diameter 4″
Side: 2″
Please let me know if you have any questions.
Thank you,
Babette