head unit

the brains of a car sound system and serves as the input for your music sources, works better when you connect up a few amplifiers and subwoofers to crank the volume and bass to make everyone else hate you and to get girls attention by driving by with it at max volume and if you have a over powerd sound system in ur car you will be the coolest kid in school and you can make your friends jealous of you, car sound systems are fucking rad.