Description: Streamline design: The main unit has aluminum alloy shell, and the extension has built-in speaker.This system has simple connection for DIY operation. Highg quality: This system has top-quality speaker and high-sensitive microphone. Especiall the metal tube microphone is deal for the counter and the dual-way inter-communication. Good performance: The voice from this system is clear,and natural. There is a switch ony for the volume control. Advance technique: For this system,we adopter the advanced microcomputer from U.S.A Definite instruction: The indicating lamp shows the track's working status. Simple operation I: Easy for dual-way intercommunication without pressing button. Simple operation II: This system haw two knobs to adjust the inside and outside volume. When the indicating lamp for audio turns green, the inter communication could begin. Simple operation III: You could record the voice through record jack. Best Choice: It suitable for the Bank, Securities Company , Hospital, Station where the security glazing is installed. Feature: Dual-way intercommunication Slim fit design of speaker Anti-interruption and noise Dual-way audio record Performance Data: Brand: RL Working voltage: DC9V/0.5A Input voltage: AC 110-240V Cable length: 160cm Main sound (sub sound): 2W, 100Hz-15KHz Inside microphone: -48db 20Hz-20KHz Outside microphone: -48db 20Hz-16KHz Main box size: 158x87x46(335)mm Deputy box: 91x77x23mm