Features: 100% brand new and high quality 30 to 130dB, the product operation is very convenient, it can be used only by connecting the power supply. LCD display with backlight, this meter can be used to measure noise in various occasions and accessories, such as factories, offices, homes, traffic routes, audio, air-conditioning refrigerators, et. Power on, short press the "switch machine" button to shut down, long press the "switch machine" button, automatic startup function: the product will automatically turn on when connected to the power supply, long press the "switch machine" button, it will shut down, if LCD display appears The numbers on the screen do not jump, and garbled characters appear. When using the sensor, please pay attention to whether there is any blockage of foreign matter. short press the "horn button" to turn off the alarm and the red light goes out, then press the "horn button" to turn on the alarm, and the red light is on. Package Includes: 1x SNDWAY Digital Sound Level Meter Specifications: Material: ABS Type:SW525A/SW525B(with storage + USB communication)/SW525G (with storage + USB communication) Green Light note: Please allow an error of 0-1cm due to manual measurement.