These are old aluminum windows with single pane glass held in and "caulked" using a gray colored vinyl/rubber type strip of material which is triangular shaped but has indented crevices so that the material snaps into place sealing the window pane. It is used instead of caulking. I don't know if it is a glazing strips. It is 5/16" by 3/8" by 1/2" and apparently could be cut into any length strips that you need. I have been unable to find it anywhere.
I found a roll of this stuff at Home Depot. It was $21 for a 12 ft roll.
You cut off the length you need and it slides into the little groove then you put the frame back together by pushing the aluminum back in plac over the plastic corner "joists". Try their web site( i haven't checked) if there isn't a home depot in your area. Lowes is another option, but I typically don't shop there ( HD is closer for me)
You could use the rope caulk-- thing is-- that strip is all that is keeping the glass in the frame.
good luck