This is the genuine BMW downpipe gasket situated between the downpipe and mid-section of your exhaust, which is highly recommended to replace when replacing your sport or decat downpipe on your BMW F87 M2 Competition F80 M3 & F82/F83 M4 with the S55 engine.
Compatibility - S55 Engine only
BMW F87 M2 Competition 2018 - 2019
BMW F80 M3 2013- 2019
BMW F82/F83 M4 2013 - 2019 (inc. CS and GTS models)