ITEM NAME:MT30 High Precision Digital Luxmeter Luminometer Photometer Light Meter A#S Product Description Description: Features: Lock screen function (hold), maximum / minimum measurement. Automatic range auto, and manual range switching. Automatic shutdown function (no operation in 15 minutes). The meter will automatically detect the battery capacity. When the low power symbol is displayed, please replace the battery in time..When using, the photodetector should be kept clean. The reference standard of light source test is at the top of the receiving sphere. If you need to manually switch the range, long press the hold key to cycle and select the range.