I've been trying to find an answer to this via the search, but must not be doing it right...anyway...

I recently acquired a nice 14" blue Vistalite Concert Tom shell for a reasonable price, and decided to bring it back to life. (This may lead to a Life Saver collection of Vistalite concert toms. Or not.)

I've got the right small Classic lugs, and all the pictures I can find show them with a gasket on a Vistalite shell. But I can't tell what they're made of, and if they're always cut to the same size as the lug, or just to hide the internal spring.

I figure I can make a pattern and cut some once I know these answers, but, as usual, knowing is half the battle....