Bluetooth Connection Procedures: The decibel meter can connect to your smartphone via the app, enabling unlimited data recording when connect the meter to the app that works for both ios and android devices. DANOPLUS decibel meter itself can record 20,000 groups data and no need to put your phone next to the meter, long press MAX MIN button until the dBA is flashing, and then connect to your phone to view and export the data The wireless db meter can accurately measure sound levels ranging from 30 to 130 dBA, with an accuracy of +/-1.5 dB and a resolution of 0.1 dB The wireless db meter designed with calibration function, with 94dB at 1KHz standard sound source This Sound Level Meter is compact and functional design, easily to carry and widely using for Classroom, Home, Office, Workshop, and etc.