1946 Spartan trailers used this gasket on their front fixed windows and on their other fixed windows, like porthole door windows.  Later 1940s Spartans also used this seal, but not on the front windows.  They continued to use it on their porthole door windows and other fixed windows.

The seal wraps around the edge of the plexiglass or glass and then is pressed up against an aluminum stop in the trailer opening.  A retaining strip is then attached on the interior to press the gasket and plexiglass up agains the stop firmly.  The round bulb on the U-shape profile rests on top of the stop and is exposed to the exterior.  Overall this gasket is approximately 1/2" high.

The original seal was designed for 1/8" glass but replacement glass is usually thicker.  Ours is designed for 3/16" glass.  The seal will not work well with original 1/8" glass in portholes. 

Silicone rubber is the most stable of gasket materials and is ideal for this application.  Adhesives are generally not needed for this seal, but if you would like to add some for extra assurance, use a small amount of black or clear silicone caulk.

Priced by the foot.