Some independent stereo manufacturers including JVC, Pioneer, Kenwood, Alpine, Sony, and Harman Kardon also have iPod-specific integration solutions. Alternative connection methods include adapter kits (that use the cassette deck or the CD changer port), <answer>audio input jacks</answer>, and FM transmitters such as the iTrip—although personal FM transmitters are illegal in some countries. Many car manufacturers have added <answer>audio input jacks</answer> as standard.
What has become a standard inclusion in cars for several different auto companies?
audio input jacks