"DanG" wrote

Sorry, Ed, the holes are for the drive lugs. They are not anywhere near
long enough to knock out slugs, though I suppose the correct punch could
be used to do so after the hole saw is removed from the mandrel. Failure
to use the drive lugs will cause the hole saw to jamb onto the mandrel
tenaciously.

I stand corrected then. That's what I've always used the holes for. I guess
I never had a hole saw that came with drive lugs because I've never seen
them, I usually buy the cheap stuff when I think a tool may be used just
once or twice.