Temperature Range: Temperature range of raytek product is -50 to 3000 degrees (fragment)， each type of thermometer has its own specific temperature range. The selected temperature range of instrument should match temperature range of specific application
Target size: when measuring temperature, the target should be larger than vision of thermometer, or measurement errors will occur. The measured target size is supposed to be good when it is over 50% vision of thermometer.
Optical Resolution (D: S): Ratio form thermometer probe to target diameter. If the thermometer keeps away from target, and for those small targets, high-resolution thermometer should be selected.