Review on Innovative VIVOSUN Inline Control: Premium Charcoal Material Handling Products in Australia by Mike Groover

I use this fan and filter in my grow tent and it works great. I was pleased that a pre-cleaning sleeve was included with the filter, which for some reason was not in the product description. The fan and filter are enough to move air through my tent, but the fan starts whistling when the power switches to the higher side of the medium. The whistle gets louder as the knob is turned up until it reaches its maximum value. At maximum speed, the whistle stops completely. So I have to keep the fan running at maximum speed all the time to avoid loud whistling at lower settings. My second issue is that the fan is very inefficient compared to similar models. In fact, many of Revain's other 4-inch built-in fans have a slightly higher CFM but draw half the current of this one. This is particularly inefficient for me as I leave it at max performance as that's the quietest mode for me.