They look like normal washers, but nothing could be further from the truth. The part number may start with an "N" from the German word Normteile, meaning "standard parts", but these washers aren't quite so standard.
They have an internal diameter of 7 mm, equivalent to an M7 washer, but an external diameter of 12 mm, equivalent to an M6 washer. What's more, they have a hardness of 200 HV, whereas a standard washer has a hardness of 140 HV.
They have been used where an M7 washer would not suffice in terms of external dimensions and an M6 washer would not suffice in terms of internal dimensions, and where a standard M6 washer would suffice in terms of dimensions but the steel was too soft.
We can't say it often enough: even if it seems to be a standard particle, use only the mounting materials prescribed by Volkswagen and no other solutions that deviate from them.
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