Specifications:Working current: Tester: 10mA Receiver: 30mASignal transfer mode: Digital signalSignal output level: 8Vp-pSignal transfer distance: 3KmBattery: 2 x DC 9V Battery (NOT included)Size: Transmitter: Approx. 126*49*34mm/4.96*1.92*1.33in Receiver: Approx. 178*40*25mm/7*1.57*0.98inWeight: Approx. 311g Features: This cable tester is suitable for RJ11 RJ45 UTP STP. Judge continuity of the cables or wires. Receive the tone signal on the cables or wires (telephone line). Identify the state in the working telephone line (clear, ring, busy). It comes with an earphone support to enable service technician to work conveniently and comfortably in noisy environment.