The Kenwood PC-1A phone patch provides a connection between the transceiver and a telephone line. It is designed to provide high isolation between receiver input and transmitter output. Impedance levels (nominal): Line 600 ohm, Receiver Input 8 ohms, Speaker Output 8 ohms and Microphone 50k ohms. Microphone input and output is 8 pin. 6 x 2.25 x 5.75 inches.