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 05/Set C
ENGINE 166, 266, 640, 668
Use:
Assembly cartridge
for removing and installing three-grooved valve keys.
In combination with assembly tool for valve springs 111 589 25 61 00 and plate 668 589 00 32 00