"The MS - 802 secondary standard pyranometer is the ultimate reference sensor to measure global solar irradiance with the highest precision. It's robust brass mechanical construction makes it a durable sensor suitable to be used in harsh environments. The MS - 802 is used as standard for PV research and climatology studies around the world. In combination with a sun tracker (STR-series) or manual shading ring (RSR-01), respectively the global normal incidence (GNI) and diffuse (DHI) irradiance can be measured. The MS - 802F is an MS - 802 with integrated ventilator unit to improve the perfomrance under various environmental conditions (prevents or minimizes the effect of dew, rain, snow ice and dust).","• Secondary Standard Pyranometer •Fast Response Time (95% < 5S) •Temperature Compensated In A Wide Temperatue Range •High Quality Optical Glass Domes For Proper Cosine Response •MS - 802F Is An MS0802 With A 110 VAC\/12 VDC Ventilation System To Prevent Any Possible Influince Of Frost, Snow And Dust"