windshield gasket lock strip diameter?

well if you made the same mistake I did....

I cut the old gasket out not noticing the small round insert that runs in the middle of the gasket. mine was on its way to the dump before i realized that I was going to need it, dooh!!

I was trying to find a cheap gasket when i read "does not come with locking strip" ??? so after some research I found a place that had them but can't for the life of me remember what the site was..

but I don;t think I remember being offered in a 1/4" something like 3/8 and 5/16..
I'll keep looking .....