The SM137 is a versatile, flat-response cardioid condenser probe microphone. 
The SM137 has an ultra-thin diaphragm for a frequency response that combines a smooth high-end with a tight, controlled low-end and a 15db pad for natural sound reproduction in both acoustic and high volume performance applications. 
 
FEATURES
Ultra-thin diaphragm for smooth high end and tight, controlled low end
15dB pad for performance consistency across a wider range of high SPL sources
Low self-noise and transformerless preamplifier circuitry