Type ECM-10B is an ultra-miniature omni-directional electret condenser microphone only 6mm diameter & 5.2mm thick. Specifications Response Omni-directional Frequency response 50 Hz to 13k Hz Sensitivity 60d B plusmn 3d B 0d B 1 Vmicrobar at 1k Hz Vsubccsub 4.5V Rsublsub 1k Omega Impedance 1k Omega maximum SN ratio 40d B Sound pressure level 120d B maximum Power supply 1.5V to 10 Vdc Recommended voltage 4.5V optimum performance Current drain 0.5m A