they are 3 layer steel with bore rings.

on the early gaskets, if the bore rings wern't lined up properly, the gasket wouldn't seal properly and would fail.

the latest revision of the steel gasket has the bore rings aligned on a thin layer of material between the steel sheets and therefore won't move out of place

all faces must be impecably clean and flat when fitting the gasket tho - or it won't seal and will fail


by far the gasket of choice tho - its what i'll be having on my new engine next year