Rubber Seal between Convert Top and Windshield Frame

[Nitrate]

I'm in the process of replacing this rubber seal. When I removed it from my car I found a hard plastic hollow tube about 3/8" in diameter running the full distance end to end. It ran inside the seal's hollow chamber. The seal is the standard aftermarket sold by the usuall Fiat vendors. Is this plastic tube supposed to be there or was it an addition by the installer or PO? Anyone purchased one that came with this 3/8" plastic tube included? RB