There is a drilling in the side of the plug in which you can put a size 3 Allen key or a Torx key T10 (usually found in the your BMW toolkit) in order to fit and remove it.
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Also referred to as oil filler cap.
Cover for the clutch fluid reservoir. Honed from top grade...
Fold Away Lever Kit by Magura (clutch and brake lever)....
Cover for the brake fluid reservoir. Honed from top grade...