... our product patent Specification: Model No.:AD-2006WDLdescriptionSlap-up two way window intercom kitsDimension:Master Station Size: 152x80x77mmSubstation Size ... & exterior have built-in mic,automaticlly hand-free two-way speaking without external mic.3.Use high-quality ... in difficult window talk,such as bank, Securities Company,post office,railway station, insurance company,ticket office,hospital, ...