I used the long aluminum cover to replace the missing plastic one on my Caravel
. I shortened it and used the section I cut out as a flange to rivet the halves back together. RJ Dial has a nice step by step for this on his vintageairstream.com site under the caravel
. Cutting the vent neatly is a challenge. I drew lines with a sharpie pen and cut with a hacksaw. Others might use tin snips. I also made a template first using craft paper. Cut, trim, plan your rivet holes, make mistakes and start over using the paper up on your roof until you're happy. Then trim your cover to fit the template. My original rivet holes wouldn't line up with the new covers flange. So I put Vulkem-sealed olypic rivets in the old holes and planned my new cover to be slightly longer to hide the old holes. Don't forget to clean and seal the vent flange first, before you install the cover. Also consider adding screen to keep out critters. Finally, before you install it, look at pictures of other cover installations to figure out which end goes forward. The cover isn't symmetrical.