STC-1000's have a waterproof sensor on a long cord, I recommend putting the actual unit outside the incubator and the sensor wire, plus the 2 power leads for the element through a hole to the inside. In my coolerbator, I just put them through the drain hole. On the inside, tape or otherwise attach the sensor wherever you want, but presumably in the airstream in front of the fan and heating element. One nice thing is that you can "tune" this my easily moving the sensor. With regular thermostats, you have to move the entire unit if you aren't getting the right temp control.