A great Lavalier that also excels for miking acoustic guitars.

The Audio-Technica AT831B Lavalier Condenser Microphone clips on to provide crisp, full-sounding voice or instrument pickup. Operates on battery or phantom power. 6' cable to power module. Cardioid pattern. 40Hz-20kHz frequency response. On/off and roll-off switch.

Audio-Technica AT831B Lavalier Condenser Microphone Features:

Clip-on Lavalier mic also excels in acoustic guitar applications
Provides crisp, full-sounding voice and instrument pickup
Operates on battery or phantom power
6' cable permanently attached between mic and power module
Cardioid polar pattern
40Hz-20kHz frequency response
Open circuit sensitivity: -44dB (phantom), -45dB (battery)
Low frequency roll-off: 80Hz, 18dB per octave
Signal to noise ratio: 65dB, 1kHz at 1 Pa
Includes foam windscreen, clothing clip, instrument adapter, power module, battery, and protective case

Audio-Technica AT831B Lavalier Condenser Microphone Includes:

foam windscreen, clothing clip, instrument adapter, power module, battery, protective case