Just noticed there is a contradiction between Tim's old sales literature and both the snap-on catalog and the Google book link.
The original literature calls the type with the round portion in the center "Type A"
Both the others call the round center one type G, and type A is the more plain hourglass shape.
I'd trust the later, but odd to see the confusion.
Again, from what I've seen we use the plain hourglass looking ones, what snap-on calls type A
Grigg
