Rex All Seasons Top made by the REX co. of Connersville, Ind.. made for 1920-23 Buick roadsters and touring cars, with all flat glass side windows for winter time driving.

 Rex  made tops for 

 1920 and 1921 Buick Roadster, 5 and 7 passenger Touring,

 1922 and 23 Buick 2, 5, and 7 passenger, the Sport Roadster and Sport Touring

 

http://progress-is-fine.blogspot.com/2021/11/rex-winter-enclosure.html

https://forums.aaca.org/topic/338391-any-1920s-open-buicks-with-rex-closed-car-removable-top-still-out-there/

https://www.icollect247.com/item/170908/Buick-Car-Tri-Fold-Brochure-1924-Rex-Tops

https://www.buickheritagealliance.org/index.php/archives/search/rex