The P300 precision blackbody radiation calibration source has a 2-in. aperture and uses a uniformly heated spherical cavity to achieve an emissivity value of 0.999 or better over its entire temperature range. Manufactured by Pyrometer Instrument Co. Inc., it provides temperatures between 100 and 1200 °C with ±0.25% accuracy of reading ±1 °C. The unit requires 1 h of warm-up from room temperature to 1000 °C and can be operated at ambient temperatures between 0 and 44 °C. The P300 uses a digital PID controller to display and hold the temperature to within ±1 °C. Suitable applications include calibration of IR thermometers, thermal imaging systems and spectrographic analyzers.