The rear view mirror glue is very hard and very very thin and requires the metal piece to be completely smooth and flat, this bracket is perforated so glue can pass through it to stick nicely.

The total thickness of the glue bond is about 1/8 inch

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)