The primary function is to convert toxic gases and pollutants to harmless gases that help to purify and treat car exhaust. Using it can help improve exhaust gas velocity and save horsepower and torque. Fitment 2009-2014 Ford Expedition 5.4L2011-2013 Ford certifications:OBD-II , Federal EPA , Non-CARB, material:Stainless steel, restricted states:California, new york, colorado, maine, fitment type:Direct replacement, inlet type:2 Bolt Loose Flange with Spherical Flare, outlet type:Spherical Flare Loose Flange, oxygen sensor location:Post-catalyst, engine:5.0L, engine:5.4L, substrate:Ceramic, interchange part number:53904, 50567, 3041025A, 3041025B, 645281, 645282, 30496, 30497, warranty:5 years or 50,000 miles limited