Extech 421502 Information The Extech 421502 Type J/K Dual Input Thermometer with Alarm is a high-precision, dual-input thermometer that features a dual display, programmable high/low audible alarms, Min/Max/Average readings, Data Hold, Relative function, and differential temperature measurement between Type J, Type K or both J and K. It comes complete with two Type K bead temperature probes, protective holster with stand, and a 9V battery. Introduction The Extech 421502 Type J/K Dual Input Thermometer with Alarm is a versatile tool that can be used for a variety of applications, including HVAC/R, food processing, manufacturing, and more. It features a dual display that shows both the current temperature and the maximum or minimum temperature that has been recorded. The thermometer also has programmable high/low audible alarms that can be set to sound when the temperature reaches a pre-set value. This makes it ideal for monitoring temperature levels in critical applications.