Full 40 channel operation;ANL switch;PA/CB switch;Instant Channel 9;S/RF meter; California Residents: WARNING Compact mobile CB Radio with PA/CB Switch.Uniden's Professional Series PRO520XL Heavy-Duty CB radio offers a full 4 watts transmit power, with RF gain control, and 40-Channel operation in a compact rugged construction CB radio.The PRO520XL has a front mount 4-pin electret microphone with extra-long coiled cord, S/RF LED meter, instant emergency channel 9, transmit indicator lights, Automatic Noise Limiter switch, Public Address switch, Volume control, Squelch control, and more.Extremely popular for Industrial, Commercial, and Off-Road use. Easily fits in most any vehicle because of its compact size.Built-in External Speaker Jack allows connecting to an optional external speaker, and you can use the Public Address function to be heard outside your vehicle with an optional PA speaker.