Extech hd200 digital thermometer k type extech hd200 p the extech hd200 is a differential thermometer with innovative technology it can detect the temperature differences with the contact thermo element measurement sensors with the ir thermometer sensor you can conduct contactless measurements of surface temperatures it possesses a wide three line lcd display in which the ir measurement t1 t2 and t3 or the temperature difference measurement t1 t2 t1 t3 or t2 t3 are shown the temp