Exeze Pico 5 FM Transmitter

What does it do?Which devices is it compatible with?How do I use it?Where can I buy it?What if I can not find any unused frequency?While driving, static and distortions occur after a while / intermittentlyHow far does it transmit?I can not hear my music due to static and distortionsWhat audio files does it work with?Is there a guarantee?Is it legal?What if I have a problem or question not listed here?