WARNING: This page is about a different car, the 2009 Mercedes-Benz E350 and 2008 Mercedes-Benz E350. However, it is still accessible from the selected car via links, so may be relevant.
FG 05/15/Set B
ENGINES all
Further use
FG 05/Set B
WS05.00-N-0155B
Use:
Magnetic pin dia. 6 mm for remove/install of the valve keepers, to remove and insert small parts.
Fig 1: Identifying Magnetic Pin (210 589 00 40 00)