What does the RGB (IN) connect to?

Hi I'm about to install my video interface for my 2008 BMW 550i. I purchased the 813649 interface and was wondering what the RGB (IN) connects to or if I need it for anything?
Thanks!
Thanks!
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divinemark wrote:Hi I'm about to install my video interface for my 2008 BMW 550i. I purchased the 813649 interface and was wondering what the RGB (IN) connects to or if I need it for anything?
Thanks!