For professionals who strongly need twoway speaker and smart set to assist to complete work fast and easily. >Data detection and locked with audible and LED alarm >Data locked override >High voltage detection in 3 levels and locked with audible and LED alarm >Data safe high impedance monitoring > After disconnect from test first line, this can reconnect and test other lines without pressing key >Two-way handfree speakerphone >DSL Filter can off-hook without disrupting data services. >DTMF Tone and pulse dialing >12 number speed dial memory, 1 Last number redial , Hook flash, Pause, Microphone mute. >Speaker and Receiver volume adjustable in Talk and Monitor modes >DC Line voltage level measuring . >Polarity indication >Low battery indication >High standard Testcord set with bed-of-nails and piercing pin clips. >Weatherproof case IEC IP67>Required battery 9V (not included)