Industrial Covert Unlimited is in its 20th year of operation. CU1.COM has been up since mid 1999. Great security & CCTV products and people who answer the phone!
Check this out!
ETS SM7 Complete 4 Zone Audio Surveillance Kit W/ SM1 Microphones and SM4 Switcher/Mixer/Amplifier
The ETS SM7 is a complete 4 zone, manual switching, audio surveillance system with a built in speaker and headphone jack. This audio surveillance kit can be used independently for monitoring live audio or with digital recorders for recording and playback.
This kit has two modes of operation: Switcher (select one of four zones) or mixer (select any combination of zones).
This audio surveillance kit includes 4 SM1 microphones as well as the SM4 switcher / mixer / amplifier for live monitoring options, including use via speaker or headphones.
Features of this kit include a 25' pickup radius from the microphone, adjustable gain, a treble boost circuit, and 12VDC power use. So if you're looking for a quality audio surveillance kit, then the SM7 may be perfect for your needs.