A landlord from Leesburg VA says:
January 10, 2015
This part looks similar to the Capitol 800 but the curved end has a definite bead along one edge, and no 'hook' at the other edge. Mine is also larger. Color is black. It is off a metal slider window in a fairly old condo.
Paul from SWISCO responded:
January 12, 2015
Good afternoon! Our 55-127 vinyl snap in looks very close to your drawing. What do you think?