these are the things that u plug into the headphones jack of a cd player or mp3 player and u can transmit the track over the radio and pick itup in ur car, for example. I got a belking one and it absolutley sucks.im going to return it and get my money back. now my question is is do they all suck. i'm thinking of getting an itrip (for my ipod mini) and using that in my car but i want to know if it is even worth it. anybody ever try them?