First Electronics Development Co., Ltd.

MW-303A  Concrete Microphone
Voice in the next room can be heard clearly breaking through even a thick concrete wall.

Ultra high sensitive microphone :
This is not a conventional acoustic amplifier, but quite a new type of professional microphone.
The device changes direct vibration sound of wall to voice vibration sound.
An essence of electronics technology combined with acoustic vibration technology.

1. Insert the microphone plug into the MIC-JACK, and the earphones plug into the EAR-JACK. 3. Press the microphone on the Wall, Glass, Door, etc. You can hear transmitted voice in the next room.
2. Turn the volume knob to the right to confirm a snapping sound, LED lamp is light on by which the device becomes "ON" position. The volume is increased when the knob is turned further to the right. 4. After the use, turn the knob to the left to confirm snapping sound to cut power source.

For better performance, do not touch the microphone and its wire, fingers, joints, etc. For ideal performance, the microphone should be fixed on the wall, etc. by adhesive tape.
When the sound is heard distorted, Battery should be replaced with a new one. Slide out the cover on the back of the device. Insert the battery in the correct position. Battery for this device is LR-1 or R-1 (1.5V×2pcs).