Link is here:
Soft Top window renewed - Pelican Parts Technical BBS
& here
Soft Top window renewed - Pelican Parts Technical BBS
Make sure you get Marine grade u.v. resistant clear vinyl. There are several brands like Strataglas for example.
Thicker is not better- just muc hrder to sew. Clearer is not better. The most u.v. inhibitor is the best.U.V. is what causes the yellowing and cold makes it even more brittle.
https://www.sailmakerssupply.com/prod_detail_list/window-material