BobBong is right about CanFan. They make good filters and good fans. I use both. At some trade show one of theirs out-sucked 2 of some other brand for the same supposed CFM. My understanding is however, that CanFan carbon filters make it difficult to change carbon, unlike some other brands. Haven't tried it yet on mine, but I'm probably due. Maybe I won't worry about it until I start smelling weed venting to the outdoors, which hasn't happened once in the four or five years it's been since I installed it.

Vortex is an excellent brand which I also use.

And MVP is absolutely right. Always overbuild, at least a little, when it comes to venting. You will be so sorry if you try to scrimp and save in that dept.