The 'E' Type Forum

I'm about to replace the "A" post door seal guides on my early '64 DHC and the replacements from the usual suppliers has a notch cut out near the top as in this picture? Why is that? Am I missing something?
Many thanks.

I am not sure why it is there. It sits over a seam area so maybe just to stop interference. I put the notches in mine when I fabricated them for my car just because they were there on the rusted old ones. You can see the notches just below the upper clamp.