I'm using the same $8 HD hot water heater thermostat as seen on most of the homemade bators here. I would expect them to have somewhat good accuracy. I realize, of course, that we are heating lightbulbs, not hot water. Mine is pointing directly to the "2" in the "52C" mark (I'm reading it upside down and through the lightbulb, so I think that is correct. Its the one on the bottom) My temp is holding at 96.5.. still too low. I know I need to turn it up a bit, but I'm worried about it being too high as well. I know when I first turned it on, it was just perfect. Then I fooled with it to adjust for a 25w bulb. Now I'm back to the 40w and its still off. Just wondering where other peoples are set to get to the correct temp for their bators.