FYI: A cheap replacement option for the top two screws on an exhaust manifold with a B pipe. Easier to tighten. Confirmed that the product I received (30mm from AMZN, though 25mm arrives today and will be what I keep) fits and works, but YMMV. The combined hex head and flange is thicker than a normal hex head plus washer.
https://www.amazon.com/dp/B083HW94GK - Has serrations on the flange
https://www.newegg.com/p/0PS-008N-04DD7 - No serrations, but more $/each
https://www.amazon.com/dp/B083HW94GK - Has serrations on the flange
https://www.newegg.com/p/0PS-008N-04DD7 - No serrations, but more $/each