This cassette adaptor is the easiest most convenient way to listen to any portable audio player through your car39s stereo plug the audio jack into the headphone port of your iphone ipod mp3 player cd player or other portable audio device insert the cassette adapter into your cassette player and start jammin39 to your tunes in the car listen to music from your mp3 player iphone ipod or smartphone through your car39s cassette player simply connect the 35mm jack on the cassette