Reddit reviews Sound Level Meter Acoustical Calibrator 94dB & 114dB output levels for 1 inch and 1/2 inch mic

Two output levels of 94dB and 114dB with Output frequency of 1000±0.1%Hz (allows calibration with A,B,C or D weighting networks or linear)Fits ½ inch and 1 inch microphones (includes ½ inch adapter)Easy One handed operation with low battery indicatorBattery life approx. 100 hours and Conforms to IEC942 Class 1Altitude Effects: Approximately0.1dB decrease for each 2000ft increase in altitude from the sea level to 12,000ft elevation or comparable atmospheric pressure change (approx. every 50mm of Hg decrease)