The 3.5mm audio cassette is designed for who has a cassette player in his car but wants to play Disc or MP3. Stereo mini plug connects to your portable player's headphone output to channel-rich digital audio through your existing car stereo. Works with most portable CD and MD player. This adapter is ideal for use in cars - Works with MP3 CD MD DVD?Players iPod PSP NDS etc (anything with a 3.5mm earphone or audio output jack) - Frequency Response: 30Hz ~ 20kHz - Connector: 3.5mm Stereo Jack - Cable Length: 120cm . Difference between this one and the more expensive version: this one's sound is not as crisp and is suitable for?playing voice audio contents and radio quality music contents