Seal front door to A-pilar

[Kodjo]

I redid all the seals in my '69 Avanti II. No leaks except the hinge side of the doors.

I applied the seals that are sold in the usual shops. On pictures on the internet, I see one mystery seal I do not have nor can find it anywhere. Does someone can give me more info on this part? Can I make it myself or buy somewhere? Thanks!