I put this in my Chevy Express extended cargo van. I cut a 14"x14" hole in the roof with a jigsaw, and went to installing this vent fan. First I built a square frame with 2x2s so there was something for the fan to attach to, along with the sheet metal roof. The rest of the installation went as expected. It took some time to lay the butyl tape evenly on the corrugated van roof, but once done, the rest just drops into place. The only part of the install that I had to work over my head, was screwing in the final interior trim piece. That works for me.
Wiring was simple and straightforward, with no issues. I used a couple of wire nuts and tucked the wires under the plastic trim.
At the lowest of the four speed settings, I cannot hear the fan operating at all. Next bump up and I can begin to hear a whirring sound, but it's still very quiet. Even at the highest setting, it's quieter than any of the Fantastic Fans in my "Squarestream" trailer.
I will be replacing those old things with the MaxxFan vent fans soon!
UPDATE:
After nearly two years of use, I'm still pleased with the performance of this fan, but the metal "screw" that raises and lowers the lid has broken. I can lift the lid from the outside and place a prop under it to hold it up, but no more opening and closing from the inside. ☹ï¸

So far I've only ran this fan for a short period of time due to the weather. I must say that it is very quiet even on full power. At its lowest setting I can't hear it running.

Love these. This is my second for this camper, just plugging all the roof holes with this fan.. Its quitish and does the job evacuating air well.

Huge difference. Can't believe how much more are it moves vs the stock fan. Also love the option of being able to leave the vent open without worrying about rain coming in. Keeps the camper cooler when not in use, because you can leave it open. Excellent quality and not difficult to install. Hardest part was getting the old sealant off without damaging the roof men.

This is much better than a regular RV vent fan and an add on hood on the roof. When this is closed, it does not stick up nor look bad. Can be left open in the rain and will not allow water to enter. I am very impressed with the design and quality of this fan. If someone short will be using the RV, I suggest spending a little more money on the model with a remote control.