The professional driver's choice for over 50 years RoadKing mobile communication devices and accessories keep you clearly connected. The combination of professional-grade durability, convenient capabilities and reliable technologies have set the professional driver standard for over fifty years. The original RoadKing has been around since the creation of the interstate – over 50 years! With superior noise-canceling technology and rugged design, RoadKing quickly became the popular CB microphone choice among professional drivers. We understand the unique needs of today’s professional drivers and what they look for in mobile communications. For these drivers, the CB radio is an essential element for communication and safety while on-the-go. RoadKing is your trusted source for reliable, affordable CB communication equipment The RoadKing RK56B has a 4-pin connector, black cycolac case and Noise cancelling dynamic microphone with a flexible black cord. 2 position momentary slide switch with normally open contacts. Frequency Response: 100Hz-8kHz, Output Level @ 1kHz Open Circuit: -72dB (ret. 0dB=1V/Ohm Bar) Power Level: -55dB (ret 0dB=1Mw/10 Ohm Bar) Output Impedance: 2000 Ohms (Matches 600-5000 Ohm Inputs)