I've supplied them to a friend who performs work on his own cars - he's fitted 2 MLS gaskets (one to his Mother's 25, another to his own 75) and an Elastomer gasket to his ZR160 track car (low liners due to an epic boil-over).
All have been fine for some time - and I expect them to be so in the future.
I of course back these products up with my usual guarantee of quality.