PLAY X STORE USB Female to 3.5mm Jack Male Audio Converter Adapter Only Support U Disk,and only use in cars. USB 2.0 female: connect the Flash Disk, can read the mp3 form Flash Disk 3.5mm male: plug in the car AUX port. *IMPORTANT*: You'd better not store too much on the U disk while using.Do not store other documents inside U disk and do not establish folder. Please make sure your car have the mp3 decode function, that can read the mp3 file from U-disk.