Soundkase FM Transmitter for iPod & MP3s and Auxiliary Input Devices Combination vehicle FM transmitter/charger for portable audio devices 4 selectable transmission channels: 88.1, 88.3, 88.5, or 88.7 MHz Plugs into car's 12-volt cigarette lighter adapter to charge audio player Works with iPods, MP3 players, personal CD players, laptops, and other audio devices Operating range of up to 30 feet (10 feet or less for best signal); 90-day warranty