Recently bought a load of Tegiwa washers and bolts and was thinking of swapping the cam cover bolts just took one of the bolts off and it had like a rubber grommet on it, to me a bolts a bolt but thought I would ask on here first.
The rubber seal and metal washer can be separated from the bolt but the bolts are special, they are 10mm m6 but have a wider shank/shoulder to bottom out when securing the cover...