GM-550 is an industrial infrard themometer, an ideal tool for long distance measurement. All the functions as belowing:test range from -50? to 550 ?, emissivity adjustable,LAL/HAL, Max/Min/Avg/Dif, OffsetEXTRAL FUNCTIONS:HOLDAUTO POWER OFFBACKLIGHTFeaturesData holdMax/Min/Avg/DifLow/High temp here alarmOffsetLaser target pointerBacklightAuto power