These aluminum clips are replacement parts for vintage Hehr 2700 Series Jalousie windows, like those used in many early 1960s Serro Scotty front doors.  They work in Left & Right pairs to hold each 4" tall piece of glass in the window.  

For ease of reference, please measure from the lower glass ledge to the first hole. On these clips, the distance is 2-1/8".  Please carefully inspect your windows to make sure that measurement and the overall shape are the same as your other clips.  They are sold as pairs.

Original Hehr PN 013-143.

If you have an Airstream, you likely need the other style of these clips.