I have used them in the past with perfect success but that is not to say they are the best out there. Now I use the cabnet style incubators that I just build myself with some plywood treated and sealed for the exterior and the interior is styrofoam with air holes and 3 thermo stats on it, I want nothing to go wrong so i over protect, as well as 5 thermometers per a level, 5 levels in the incubator each level holds about 50 eggs. But back to the point yes they do work some they work perfect other have massive problems with them.