This is the same Coolant Overflow Tank + Washer Reservoir filler combo that is included with our 2004-2007 WRX and STI Front Mount Intercooler Kits. As a stand-alone item it helps to clean up the engine bay and tuck the over flow tank lower and out of sight. Constructed of aluminum and powder coated in a wrinkle black finish helps keep the engine bay tidy. The Washer Reservoir consists of a tubing extension, delrin base, and delirn cap. It is specific for 2006-2007 WRX/STI which has the reservoir located behind the bumper cover.