This black rubber seal is used on stationary Hehr 5xxx series windows like those on early 1970s Shasta Starflyte trailers and many other brands of trailer. 

To determine whether you have Hehr 5xx windows, look for the number etched into the frame on the exterior. The word HEHR will preceed the number and the number may have a letter in front of it. For example HEHR-M5001.  There will be other numbers following the model number.  Those numbers relate to the rough opening size and are not helpful in determing whether this seal works in your window.

Use  this rubber glazing seal with 1/8" glass. 

Order by the foot. Will ship in a continuous length.