An Eastern Catalytic Catalytic Converter is designed for Mercury Grand Marquises from the years '02, '03, '04, '05, '06, '07, '08, '09 and '10. Catalytic Converters function by catalyzing exhaust gas contaminants into water and CO2, using a metal catalyst, such as rhodium, palladium, or platinum, then venting the treated exhaust through the tailpipe. Though not easily broken, the converter occasionally breaks or fails, generally when it is hit from beneath the vehicle. Mercury Grand Marquises from model years 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 and 2010 can use this part. Other makes and models probably will not be compatible, and this component should not be installed on those models.