Amazon.comAs part of Uniden's Professional Series, the Pro 510XL CB radio offers high-performance 40-channel operation in a compact, ultra-mobile radio. This model operates on any of the 40 AM frequencies authorized by the FCC, and its S/RF meter and red-lit LED indicators help you monitor activity at a glance. A built-in noise limiter and ANL switch and squelch control fine-tune performance and eliminate noise, and the front-positioned microphone has an extra- long, coiled cord for convenient use.A bare-bones, ultra-mobile 40-channel CB Radio.Ultra-Compact 40-Channel CB Radio ANL Switch and Squelch ControlWhile communicating, flip on the ANL (automatic noise limiter) to help eliminate background noise, such as that from the car engine/etc. The squelch control also assists with eliminating noise, allowing you to set a threshold level below which noise won't be heard. Full 40 Channel OperationThe Pro510XL will operate on any of the 40 AM frequencies authorized by the Federal Communications Commission (FCC). A superheterodyne circuit with phase locked loop technology assures precise frequency control. Signal/RF MeterAdjust the gain to boost your signal level, and get a visual readout on the meter. What's in the BoxCB Radio, Microphone, Mounting Hardware, Mounting Bracket, User's Manual, Two-Year WarrantyUniden CB Radio ComparisonProduct DescriptionUniden CB 2way Radio 40CH compact