The best thing you can do is call them and talk to Fred. He will help you with everything you need. Their website can lead to some confusing decision making.
But they make a unit that only monitors the pit temp (one probe) and a unit that monitors the pit and the meat temp (2 probes). To me it doesn't make sense to get the one with 1 probe. The price is very close and the 2 probe model gives you the option of meat temp. Also, it has ramp mode. (Fred can explain). I usually tell people to use their WSMs until the are very comfortable using it without a Guru. That way if it ever breaks or the power goes out... you still know how to cook. And cook well.