A nice little fan, I bought it to work in tandem with my existing 4" fan and controller. I learned the hard way that there are EC and DC fans, and they don't match. Luckily, I was able to catch the discrepancy before hooking them up, otherwise I could have fried them. That said, I can't run both of the single controller, so instead I am running this one constantly for air exchange while the other runs on the sensor. I didn't deduct a point for my issue because I didn't do the research, no real knock on the product itself if I had investigated more before buying!