Retevis RT-9908 Dual Way Window Intercom System Bank Counter Interphone Zero-touch for Business StorFeature: Auto dual-way intercommunication without pressing any button Anti-interference and noise-free function Dual-way audio record output This model is 110 V\/220V Voltage All of our items are brand . Anti-interference and noise-free function Two-way voice intercom communications technology, automatic identification of processing speech signals during a call does not require any action Dedicated anti-side tone processing chip, with auto-mute function Application of fully automated call control, outside the machine's microphone and speakers to use the integration of design and front-line system of the host to connect, easy installation Comprehensive application of electro-acoustic technology experience, the selection of high performance electro-acoustic circuit design, the output power up to 3W, voice clear and loud voice distinguished high. Inside and outside the two-way voice signal output(recording by the bank teller), a stereo jack output mode can prevent voice recording function controlled by the power switch and the function buttons Application: bank, securities, bus station Where guard glass again theft is installe Specification: Working voltage: AC9V\/1A Main sound (sub sound): 3W Inside microphone: -48db 20Hz-20KHz Outside microphone: -48db 20Hz-16KHz Exterior size: 158 x 87 x 46cm\/78 x 20 mm Package Included: 1 x Dual-way counter interphone 1 x External speaker 1 x Charger 1 x English User manual