This is the Nitride treated crankshaft out of the 2010 Subaru WRX STi EJ257.

Nitride treatment hardens the surface of the crank, which prevents scoring caused by a piece metal getting stuck between the bearing and the crank.

By increasing the hardness of the crankshaft surface, any material which gets caught between the new surfaces is simply ground down and filtered out through the oil, potentially preventing bearing failure.

This is a brand new part, straight from Subaru!

The Subaru Part # for this Nitride Treated Crank is 12200AA430