The Sper Scientific Min-Max Thermometer is available in two models. Model 736680 includes a magnetic float reset and features dual scales of -50/50 degree Celsius and -60/120 degree Fahrenheit. Model 736690 features a push-button reset and the same dual scales. Unlike liquid-filled thermometers whose liquid can fade over time, the Min-Max Thermometers are mercury filled allowing easy spot checking of temperature in a greenhouse or other temperature-sensitive environment.