The two scales cover the 40-80dB and 80-120dB ranges, with an accuracy of ±3.0 dB. Simple to operate; one selection dial with battery test mode and easy-to-read results. Stable, reliable operation with signal oscillator calibration and a capacitance microphone. Based on the "A" decibel frequency weighting. CE Approved. Comes with a carrying case, instructions and a 9-Volt battery.