This is a Sony ECM77B lavalier microphone. It is an ultra mini omnidirectional electret condenser lavalier suitable for many different applications, ranging from news and interview to theatre and instrument pick-up. Frequency response is 40-20Khz with upper range lift for extra presence.

Directivity is optimised to ensure uniform output, regardless of direction of the sound source. The metal mesh windshield effectively eliminates both outdoors wind noise and "popping" in close miked situations.
5.6mm diameter, 12.55mm length. It can be powered either by 48V phantom power or internal battery. Impedance 100 ohms. Dynamic range >90dB, S/N >66dB.