This adaptor is required when replacing your factory fitted radio with an aftermarket CD player (E.g. Alpine, Pioneer, Kenwood, Sony, JVC Etc).
It will convert the car's original wiring plug to a standard ISO connector which fits straight into your new stereo. Simply plug one end of the adaptor into your cars wiring harness, and the other end into your new radio, with this you will be ready to fit your aftermarket head unit.