Well my box size is only like 40 square feet and I saw a deal for a Can fan brand RS4 (inline 4") for 60$ on craigslist so I decided to get that. Im pretty sure if I wanted to I could turn that into a quick 30-40$ profit on ebay but im actually going to use it, I got lucky I guess. Its 175 or 185 cfms cant remember and its pretty quiet. No louder than my 50 CFM fan that I was using before which was rated at like 3 sones. I havent put anything on it to dampen the sound other than like a 2' dryer duct which has no insulation. You can hear it while in the room, sounds like a bathroom fan is on in the room next to you, you can only really hear the light humming. Temp already went down like 15 degrees, all I really want is it to be around 90 rather than 98 and it did the job so maybe my shit will start actually growing.