I always use a probe thermometer just to make sure when I am smoking or even making meat in the oven. Cheap insurance you get the internal temp you want. I also use a thermometer that attaches to the rack inside the smoker to make sure the temp that I have set is the temp I have inside the smoker. There can be a big difference in the temp those dial thermometers that are built into smokers are showing and the temp at the meat.