It is an accessory ( not factory fit ) option for full i phone integration including phone ,texts,Facebook twitter Internet radio, music and google sat nav . Brings everything up on the cars display and charges the phone + a bit more, once the free app ( digital drive style app ) is installed on the phone. It has to be fitted by the dealer. I'm still awaiting the labour quote. I havent seen it but presume its just a module that connects to the back of the audio 20 system. Mercedes B ham ( Bham, Solihull and Tamworth ) can get it, so should be available nationwide.