Small post, screws onto side of window, rides in the plastic track
A quick learner from Washington DC says:
March 20, 2021
One of these small parts is screwed onto each side of the sash widow, and each post fits into the track in the widow frame. The post rises in the track as the sash is raised and lowered, and the sash can be rotated or of the frame on these 2 posts.
Bob from SWISCO responded:
March 23, 2021
Our closest match for this pivot bar is our 26-150. I am not certain if it would work for you, but compare the dimensions and let me know what you think.