Dial thermometer-hygrometer has a 4” stem can be inserted in a 5/32” hole to permit reading the temperature or humidity from outside the incubator.  Face is 2” in diameter with 1 degree increments from 25º F to 125º F. Cover about 1/3 of the thermometer stem with a wick and put the other end of the wick in the moisture pan to obtain a wet-bulb reading.  For an accurate reading, change the wick if it becomes dirty with mineral residue from the water.