I bought this not knowing what to expect and really like it. I will admit I’m still learning how to use it but think it has a lot of potential. the controller allows you to pre heat the unit and then adjust temp and exhaust fan speed - and the temp probe measures bean temp or at least the temp of the inside of the roating basket. I think I kept the exhaust fan to high needing to keep the temp up to raise the bean temp. I made a few batches and think they were all a bit over done. the next batches I will reduce the exhaust fan speed and see if that helps hold the temperature inside the unit high and thus turn the heater down.