This important gasket seals up the egr cooler plate at the back of the cylinder head. Ya' know, the one you forgot to install that one time you did a head gasket job and found out it's a pain to get to? Yeah, that one.
Thick, graphite coated OE gasket to properly seal the gaping coolant hole at the back of the head.
Like any OE graphite coated gasket, it gets installed dry, NEVER any silicone. The reason they are made of graphite is it needs to allow the dis-similar metals to expand and contract at different rates (the plate is cast iron and the head is aluminum). If you siliconed/glued it down, it would rip because of the different expansion/contraction rate of the different metals.