This models allow for the user to calibrate the IRt/c's (IR thermocouple) to match a thermocouple in whatever temperature range they desire. The range adjustment screw is adjusted to calibrate for temperature range of interest and material properties (emissivity). Models for non. metals (HiE) and metals (LoE) are available. Sensor Range: -45 to 1370°C (-50to 2500°F) or 260 to 1370°C (500 to 2500°F) Field ofView: approximately6 (10:1) Minimum Spot Size: - No Aperture: 20 mm (0.8") at <180mm(7") -- ½”Aperture: 13mm (0.5") at <90mm (3.5") - ¼”Aperture: 6mm (0.25 ')at <25 mm(1")