This is a set of 4 OEM Subaru Sparkplugs for the 2004+ 2.5 Liter Turbo Engine. They are platinum plugs, so they have a service interval of 60,000 miles. These are also the OEM temperature plugs.
There are two differen't plugs, so please make sure that you are ordering the correct set for the year of your car.
The Subaru Part # for the 2004 - 2007 WRX and STI is 22401AA630
The Subaru Part # for the 2005 - 2009 Legacy GT is 22401AA670