This front frame support is also known as Napoleon's hat. It is mounted on top of the front frame, in the same place as the master cylinder.
If the master cylinder leaks (or has already leaked), brake fluid penetrates between the two plates and eventually rusts.
Two qualities are available for the same part. Quality A has a correct plating thickness of 2 mm and an exact design. If you opt for quality B, you'll have to make some compromises, but these are compensated for by an attractive price.
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