I'm using a Brinsea. The display always said 99.5, but after checking with a Spot Check, I got temps from 97.9-99.9, with an average of 99.0. It was also always cooler toward the back, like AmyLynn said about cool spots, so now every time I add water, I turn the egg tray 180 degrees. I was amazed at how much better my hatch went after those minor adjustmentsGood idea. I had discussed doing that with my niece. I'll definitely give it a try now. Thanks.