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By certification 
Description
A - Length of hole on board
B - Center to Cewnter distance of two Radius
C - Overall Thickness
D - Thickness of Board
E - Wall Thickness ( if exited )
And Other Radiuses are need to know to make the quote.
This is a type of grommet which is used on cars.
It's made of EPDM rubber, it could be used outdoor for a long time.
http://www.chaoyuerubber.com/
