iPower 6 Inch 442 CFM Inline Duct Fan with Grounded Power Cord - High Performance HVAC Exhaust Blower for Grow Tents, Hydroponics, Greenhouses & Indoor Ventilation | Energy Efficient Cooling & Air Circulation Solution

I seriously don't doubt the CFM ratings for this whatsoever. It's a bit loud on high, but this is easy to fix (it's completely dependent on the ducting. No sound comes through the casing.And it's definitely a solid machine. YES it leaks a bit of air around the sheet metal connection between the front and the back, but it's pretty sturdy (and heavy). TBH though, I'm amazed my unit still works and barely any vibration...I've dropped it or it came loose and fell 5 feet and rolled another 3 feet more than once. Mine is 6" and is just awkward to hold and mount. And I put a single layer of gorilla tape or clear duct tape (not packing tape!) Around the 2 flanges. As they're only about an inch long.but semi rigid aluminum tube stays fine with a clamp. And definitely don't use anything less smooth like flexible ducting tube on the intake (see below). 12" and the blower sounded like it was really going, but it was barely moving 1/3 of what it's rated...The mount is nothing to write home about and it's good enough to mount on bungee cords hanging from a 12" L-Bracket right to a stud (it definitely vibrates on different speeds. (Get a $5 controller from Amazon. My first one wouldn't get hot running a shop vac and the second was a 4-pack for $11). And don't go below 1/2 speed (by airflow).BTW I did my research on this type of blower and you're not supposed to slow it down with basically a glorified light dimmer, but the intake restriction is how you would tweak the volume under varying loads, etc. If you block the output, it will ramp up the power to try and compensate... But very slight changes to the input really change the output while it remains at more or less constant speed. So put a grille obviously and you want something for a muffler (1 or 2 sizes larger tubing with coarse wire mesh in the correct diameter and polyester pillow fill between the rigid outside and the mesh tube, so I did 7" with a 1/2" mesh and 10 or 12" (or 2 home depot buckets long, but one might do it. Look at commercial duct silencers online for restaurants, etc and you'll get an idea what's needed physically for components.HTH