Just an FYI. I see some post with folks talking about digital thermometers and differences in temps between thermometers. All digital thermometers are not created equal. I did a quick experiment using 2 el cheapo digital thermometers, one from Radio Shack, the other from Wallie mart, an alcohol thermometer and a digital oral thermometer for kids. I checked the oral thermometer against a calibrated thermometer at work and found the display to be right on the numbers. The first el cheop digital unit from Wally mart has the sensor inside the enclosure so it was placed on the floor of the incubator next to the alcohol thermometer. The radio shack unit is an indoor/outdoor unit with a remote probe. The probe was positioned right next to the alcohol thermometer. With the incubator running, the oral thermometer read 99.6, the alcohol thermometer was ~99.5F (best guess with the scale)...the digital unit inside read 105F and the external unit 100.5F. So, from where I stand, the digital oral thermometer was the best but between the autoshut off feature and the short probe, I couldn't put the thermometer where I wanted it still be able to turn it on. The alcohol thermometer was accurate enough for my use. The el cheapo digital thermometers were unusable in my estimation. A one degree difference (displays high which means the temp is too low) would result in an extended incubation time and possibly weak chicks. The 5.5 degree difference would mean the eggs would go one the compost pile because I doubt they would hatch and, even if they somehow did, the chicks would more than likely be sickly. Obviously, fancy, high tech is not necessarily better and perhaps not even accurate. Bottom line, whatever you use, make certain it is accurate. Btw, if your using an alcohol thermometer with a paper scale, use a thin, permanent marker to add a reference mark on the glass and the paper. I've seen these thermometers move between uses as the metal clips can only be so tight without breaking the glass. This is an easy way to know if the thermometer moved up or down. 'Calibration' is as easy as moving the marks back together. Hope this helps.