I've got a hydrofarm on my ball pythons heat mat and it doesn't really fluctuate all that bad. I have it set to 90 and the lowest it gets is like 87. I've had it for about a year now and have had absolutely no issues with it. That being said I may be a newbie to all this, but I agree with everyone else I would NEVER use one on an incubator. I plan on getting a better thermostat in the future most likely a herpstat when my collection starts to grow. But as far as the cheap thermostats go I say the hydros are probably the best one out there.