1. APPLICATION AREAS This radiometer is suitable for various tests such as physical optics, window insulation, weather station, and sunlight radiation intensity. 2. ACCURATE MEASUREMENT Photometric probe for precise readings, fast response speed, and userfriendly buttons for easy use. Small in size, light in weight, easy to carry without taking up space, convenient measurement. 3. MULTIFUNCTIONAL Features data retention, overload display, compass, low voltage alert, and automatic shutdown for added convenience. Super large display with bright backlight for easy data reading, fast sampling speed up to 2.5 times per second. 4. HOW TO USE 1. Open the battery back cover and insert the battery. 2. After powering on, close the window and aim the device at the sun, the radiation value will appear on the screen. 3. Open the window and aim the device at the sun. Compare this value with the value obtained when the window is closed to understand the contrast radiation value of the sun behind the window.