Pardon my poor English. I explain again.
My controller can define the power of fan.
The fan its self is 50 CFM.
If you have a small pit, you can define the maximum power of fan as 5 CFM.
Indeed it is a trial and error process. Just set UDC=10, 20, 30, ...100% till you find the best data for your pit. Usually 3 trials are enough.
What do you mean by over priced. I find other WIFI model of 300US$, and US$400 for WIFI fan and adapter. Nothing to say my controller controls temperature of MEAT while the other controller controls temperature of PIT. Other WIFI controller has meat probes, but the meat probes are for monitoring, not for controlling. It may be more reliable and cheaper to use wireless thermometers. Please keep in mind you are smoking your MEAT, not your pit.