The M30 is an affordable, reliable 30 kHz reference microphone. It utilizes a very small, very accurate omnidirectional element, a carefully crafted stainless steel body, and innovative circuitry to deliver flat, time coherent response from 9 Hz to 30 kHz. The M30 has become the defacto standard reference for Smaart, MLSSA, SIMM and TEF. The M30 is the most cost-effective measurement microphone which you can trust. It exceeds the specified requirements for al audio band measurement systems. The M30 is a standard.The M30 comes with a measured frequency response chart which includes a value for sensitivity. Since the M30 is stable with respect to temperature, you can input this number if your program allows and be very close to correct absolute SPL. We also ship the M30 with a 'white' calibrator adapter which adapts from the M30 to a 1/2-inch calibrator adapter for field calibration.The M30 is available as amatched pair and doubles as a great sounding recording microphone. It is sturdy and reliable. The M30 is a sound investment.