The items that fit your Alfa Romeo 4C' are shown below.

Released in 2013, the Alfa Romeo 4C came with a standard Parrot radio in a single DIN slot with standardised ISO connections and a DIN antenna connection. Later in the production run in 2016, the radio was changed to an Alpine unit in the same single DIN slot and utilising the same connections, No ISO adapter or antenna is needed when fitting a radio with ISO connections, no matter what original radio is fitted.