Pioneer CD-MC20 Microphone
2010 Subaru Forester
Crutchfield Customer Review (What's this?)
Like others have said, it's Pioneer's mic for measuring Time Alignment, etc. if you want automatic TA, you need this. I'm glad I bought it as the auto TA from my new AVH-4200 really does help to create and shape a decent sound stage. It's not perfect but it does make a BIG difference in the sound. Use auto TA, and EQ your cabin to a flat response and you will have a very decent sound stage w/o tons of fiddling.
Pros: Enables auto TA
Cons: Should come with the NEX units