The problem is all the ones I see only stay on for so long and only read the temp once. You have to measure the temp on top of the eggs not from a vent hole and for that you would have to open the bator, set it over the eggs, push the button, and wait... You just let all your heat out and it's no longer accurate. Just for amusement I took the temp through various vent holes with the medical thermometer and got everything from 94F at the bottom to "high" at the top of my still air and like 98 from a hole I put in the side to help vent humidity on really humid days here. None of those are the temp on the eggs which is 102 according to my best thermometer. In a water wiggler it would work since that more accurately shows the internal temp of an egg and would not cool quickly when you open the bator just like the eggs don't cool immediately.