Top Sash (I think)
A quick learner from San Clemente says:
October 2, 2016
Looking to find a replacement for this part.
Paul from SWISCO responded:
October 4, 2016
Hello! We don't have this precise top sash guide, but I believe you can use our 18-171 if you cut the top down a little. That alteration won't affect the operation of the window.