One is a 20g glass tank with a thermometer with a probe for the hot end and a digital suction cup thermometer for ambient temps at the cool end.
The other (actually housing my BCI) is a 4x2x15" melamine enclosure with a sliding glass front, two 4" vent holes, and a small fan blowing in one hole. Measuring those temps with an acurite indoor outdoor thermometer/hygrometer.