Active Filter Anti-interference caused by high frequency. Special design to block interference caused by electromagnetic waves, high voltage electricity, wireless stations, elevators and industry with high power. DC5V 500mA power supplies included. Emitter Dimensions 102.5 (W) x 27 (H) x 67 (Fo) mm. Receiver Dimensions 91 (W) x 27 (H) x 67 (Fo) mm.