Parkside PSSP 2 A1 Montage-, Bedienungs- Und Sicherheitshinweise Seite 13

The grinding surface of centre depressed grinding discs must
be mounted below the plane of the guard lip . An improperly
mounted grinding disc that projects through the plane of the guard lip
cannot be adequately protected .
Always use undamaged clamping flanges of the right size
and proper form for the grinding disc you have selected
for use. The right flange supports the grinding disc and thus
minimizes the risk of it breaking. Flanges for cutting discs may
differ from flanges for grinding discs .
GB 13