Retekess TW103 Window Speaker,Intercom System for Business,Dual Way Voice Intercom,Bank Counter Interphone for Office,Station,School

* Independent volume control; unique dynamic sound indicator; inside and outside volume knob can separately adjust the volume * 2m extension cable with metal sleeve; 6.5ft connection line between the main unit and auxiliary unit; more reasonable to install with stainless steel wire protection tube * Easy to install; just to make a small hole of about 0.7 inches in the glass; connect the external machine cable to the host through the small hole * Voice resources input; connect the signal input port to computers, mobile phones and other devices; broadcast information for customers * Two-way voice intercom communications technology; automatically identify the processing speech signals during a call; window speaker doesn't require any action