This is the cap piece that holds the channel balance at the top of the window frame. It is 1 1/4 x 3/4 x 5/8 inches. It goes with an Alenco window. The channel balance is a 2730 and 28"
Tom from SWISCO responded:
August 13, 2015
I'm not sure if we have an exact match. Our 18-174 looks similar, and is for Alenco windows, but its dimensions seem to differ. Could you confirm?