Exhaust seal ring at the bottom of the downpipe where it meets the center exhaust section. It's also known as the crush seal because it deforms as the exhaust flanges are tightened together. Sometimes it can be re-used but because it was already crushed once you're just asking for an exhaust leak and they should be replaced.
This is an OEM Exhaust Pipe Gasket for F8X M3/M4 engines manufactured by Elring Klinger - an original supplier to BMW for many gaskets and seals. As an OEM it meets all of BMW's original design, fitment, and performance requirements and is TUV approved. OEM parts are the best alternative to more expensive Original BMW parts because they are virtually identical without the inflated price tag. This part has a two year warranty.
Sold per gasket. Order 2 for both downpipes.
BMW Fitments:
2 Series
F87 (2016-2021) > M2 Competition S55 (2019-2021)
3 Series
F80 (2015-2018) > M3 (2015-2018)
4 Series
F82 / F83 (2015-2020) > M4 (2015-2020)
F82 / F83 (2015-2020) > M4 GT4
F82 / F83 (2015-2020) > M4 GTS