WARNING: This page is about a different car, the 2009 Mercedes-Benz CLK350 and 2008 Mercedes-Benz CLK350. However, it is still accessible from the selected car via links, so may be relevant.
FG 33/Set C
/079
Use:
Pressure plate for installing the Semmer ring in the front wheel hub.
Fig 1: Identifying Pressure Disk (240 589 00 34 00)