After much research for a DC fan for the our travel trailer, I chose this one and I have no reservations. We boondock, aka dry camp (no hookups)exclusively with 2 100 watt solar panels in series recharging our batteries.  This is our choice because we patronize State and National campgrounds that typical don't provide the amenity hookups. If they do they tend to squeeze the sites together, and although we enjoy our fellow campers we prefer to be in touch with nature. Summer heat can be challenging without AC and necessitates the need to move air through the trailer. I've modified the existing bath exhaust vent fan with an improved after market fan and was searching for a window fan to induce air. This fan meets all my expectations by providing 3 speed control and good air movement. Concerning posted complaints of excessive noise, vibration, lacking documentation and poor build quality were not seen in the fan that I received. Yes it does make reasonable noise, slightly vibrates on high (not walking around though), and build quality seems appropriate for intended use. Fan is what I expected and would do it again.