I've edited the photo to show how the insulator appears as a scale drawing compared to how a regular "B" should appear. See the huge depression on the inside of the skirt? That's not supposed to be there, it's like a large circular force like a burst of air or steam pushed in there all around the insulator and forced the glass from the spot where the depression is up into the space between the two skirts, it's as though there's pretty much no inner skirt left.