Refer to the YouTube video below, and you will have a better understanding of the working principles of the catalytic converter and tailpipe. Thanks to Automotive System Description The catalytic converter's main function is to convert toxic gases, and certifications:OBD-II , Federal EPA , Non-CARB, material:Stainless steel, restricted states:California, new york, colorado & maine, fitment type:Direct replacement, substrate:Ceramic, warranty:5 years or 50,000 miles limited