it is used to test the sound levelcalibrate the sound level of environment, mechanic,vehicle,ship and other noise, etc. Application: ... .Model: ND9B Standard: GB/T15173, ANSIS1.40 CLASS2,IEC942Output sound level 94dB 114dBAccuracy: 0.3dBFrequency: 1000HzDesign for: 1", 1/2"Power ... supply:1x9V 6F22 batteryDimensions: 142x47x47mmWeight (not including battery): 275g Sound Level Meter Calibrator ND9B