This is a 4" Downpipe for the 2020+ Ford 6.7. If you have a 2020-2022, this will flow more air and is easier to install than the factory downpipe. If you have a 2023+, you will need one of these to install any aftermarket exhaust system (note: we include this in our 2023+ exhaust kits already - so only needed if you bought from someone else).