This is the OEM Subaru foam gasket found on the factory radiator. The seal helps direct the air through the radiator, and also cushions the radiator from rattling against the core support. This will also fit on aftermarket radiators like the Mishimoto pictured. (Radiator sold separately.)
Peel-and-stick installation.
Fits all 2008-2014 Subaru WRX and 2008-2014 WRX STI, plus 2005-2009 Legacy GT/Outback XT.