It's done. I have found the operating instructions. The following text is noted:
"The sound level meter is used to measure sound levels with an intensity of 30-130 dB. It is an aid for checking sound sources or for simple measurements of environmental noise and is not suitable for laboratory use or for scientific purposes. The measurement signal is evaluated according to the human hearing characteristic (A characteristic) in the frequency range from 31.5 Hz to 8 kHz. The measurement interval is switchable. The maximum or minimum value can be recorded. To suppress disturbing wind noise, an attachable windscreen is included, which does not affect the sound level measurement. does not affect the sound level measurement. The device is powered by batteries. Use is only permitted in closed rooms. Contact with moisture, e.g. in the bathroom etc. must be avoided at all costs. For safety and approval reasons, the product must not be converted and/or modified. modify the product. If you use the product for purposes other than those described above, the product may be damaged. the product may be damaged. In addition, improper use can cause hazards such as short circuits, fire, etc. Read the operating instructions carefully and keep them in a safe place. Only pass the product on to third parties together with the operating instructions. The product complies with legal, national and European requirements. All company names and product designations are trademarks of their respective owners. All rights reserved."