No refitment to car. Put one connector of the transmitter into the car lighter plug and the other connector into the earphone of MP3 (CD and MD). Then set the car radio frequency same as transmitter. The music in MP3 (CD and MD) can be changed to frequency signal and sent to the car audio system. It means use the transmitter. Enjoy hi-fi music inside your car. Mcup provides users a variety of convenient functions, you can use it to charge you mobile phone and at the same time you can still enjoy and share your favorite music on the road. Mcup has a FM transmitter in it and it can emit the audio from your mobile phone, CD player, MP3 player to radio-frequency. Just simply dock and charge mobile phone while listening your favorite music from car\'\'s FM radio speakers. Features: 1) Listen to your favorite music through the FM stereo receiver in the car 2) Dock and charge supported mobile phones simultaneously 3) Fits cup holders securely in most cars 4) Powered through car cigarette lighter adaptor 5) Works with MP3 players, CD players and other audio devices with a 3.5mm headphone jack 6) Full FM spectrum 88.1 MHz to 107.9 MHz for the clearest channel 7) Easy-to-reach power on/ off switch, frequency up and down buttons, and quick channel switch button 8) Automatic last used frequency memory 9) Tilted backlit LCD display with easy-to-read characters Compatible with the following mobile phones: Sony Ericsson (supported by mCupSE): W950i, K310a, M600i, W300i, W700i, W810i, W600i, W800i, K750i, W550i, W900i, D750i, K600i, K608i, K610i Nokia (supported by mCupN): N70, N71, N73, N80, 6680, 668, 6233, 6234 Samsung (supported by mCupSS): SGH-D508, SGH-D600, SGH-D608, SGH-D728 Motorola (supported by mCupM): E398, ROKR E1, C975, V980, MPX220, A860 Note: docking and charging not supported to MP3 players and CD players Model number: 1) mCupSE (Sony Ericsson FM transmitter, charger in a vehicle cup) 2) mCupN (Nokia FM transmitter, charger in a vehicle cup) 3) mCupM (Motorola FM transmitter, charger in a vehicle cup) 4) mCupSS (Samsung FM transmitter, charger in a vehicle cup)