Installing MaxxAir vent cover - question

I installed two last month. Didn't think too much about it--used a drill bit I had on hand, the exact size as the directions called for and all the washers etc. they included in the package--for our unit it called for the bolts, not the screws, and it was a relatively simple job. I didn't run into any issues and our Itasca Spirit is getting up there. I also replaced the screen on one of the fans as well and found the whole assembly came apart relatively easily and even more important went back together too.