iSound Smart Tune 2 in 1 - Wireless FM Transmitter with Rechargeable Battery & included Car Charger Wireless FM transmitter compatible with iPad, iPhone, iPod, and smartphones, MP3 players and any audio device with a 3.5mm audio jack Powered by rechargeable built-in lithium battery - no drain on the battery of your audio device High fidelity stereo with full frequency range of 100Hz to 15,000Hz for full bodied wireless sound reproduction. Can also be used for phone calls through the vehicle sound system. Bright LCD displays FM frequency with backlight for low light viewing. Includes soft touch key design and holds last frequency in memory even when powered off. Transmits to FM radio frequencies from 87.5MHz to 108.0MHz with PLL to ensure clearest reception even in large cities with many active radio stations.