Small electret microphone. Useful in acoustic and audio applications.
Widely-used electronic communication and audio recording device. The devices are a type of condenser microphone.
An electret microphone is a type of electrostatic capacitor-based microphone, which eliminates the need for a polarizing power supply by using a permanently charged material. Every cellphone and laptop has one embedded into it.
Datasheet: http://cdn.sparkfun.com/datasheets/Sensors/Sound/CEM-C9745JAD462P2.54R.pdf Example Audio LED control project: https://negativeacknowledge.com/2008/06/11/final-lightbar-controller/