#inline duct fan kit

I'm trying to purchase a duct fan, but I don't know the differences between these 3 styles. Which one should I choose? This is the most common style I've been in seeing in other people's tents. 4 inch 190 CFM for $48, 6 inch 390 CFM for $60 https://www.amazon.com/gp/product/B01DXYMGOM/...

Dear RIU Fams:) Our newest inline fan and carbon filter combo kits already release for some time and receive a good response. below is the article about the them. hope it is good for you guys to use them and receive a good harvest:) :hug: :hug: :hug: :hug: by the way,if you are interested to...