Hands free two-way talkback full automaticity. 1.Full metal jacket,elegance,aesthetic 2.Hands free two-way talkback full automaticity 4.Adopt high-powered mic,elegant appearance,voice is lifelike, clear;the volume of master station and substation can be adjusted separately by oneself;5.Easy installation ,there is only one wire for connecting master station and substation,the volume of internal ...