This replacement glass and sash is for the rear of Airstream trailers from 1975-1980. 

Unlilke windows on the sides of Airstreams, the glass in this sash is flat. 

The aluminum frame corners are radiused (rounded, not 45 degree miters). 

The overall dimensions 23-1/2" high x 43-1/2" wide.

It has a hinge, tracks on the sides and strike plates on the bottom edge.