Yomikoo Car USB Interface Adapter AUX in Input Switch+Wire for 3 5 Series E90 X5 X6 Best sound quality from High quality Power amplifier chip and by using the CD changer port connection Control and operate your iPod with car stereo buttons or steering wheel controls Turn off car engine and remove key from ignition, if your radio use a security code,make sure that you have the code before unplugging the radio. Unmount the radio from the dash and find CD changer port at the back of radio. Smart design and Easy to install and use