The black ring has to be aligned with the abs sensor when installed which was in first best I remember. just make sure the ring is on the side that is closest to the abs sensor after installed.

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Just BMW's - All cars and trucks was two pages long
1994 318is
1997 528i
2000 323i
2001 X5 3.0 auto
2005 X5 3.0 auto
2011 535xi auto
2013 X5 xdrive35 Turbo
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Aftermarket E53 Radio Install