JBL engineers offer a simple answer to the million-dollar question: “What button should I press to make my factory fitted car radio sound like a professionally installed system?” The JBL MS-2 is a compact, truly unique portable device designed to enhance the sound of any portable audio source before it is fed into the auxiliary input of your car stereo. A built-in microphone and sophisticated digital circuitry analyze and correct the sound of your car stereo within 10 seconds. Suitable for use with any portable device, you simply have to press the “magic button” to dramatically improve the way your car sounds.