Screen Door Replacement Part

Seeking a plastic guide that fits into a track on the side (at the top) of a window that itself fits into a metal storm door of unknown manufacture. The attached photos show the part itself and how it functions on the door frame. The part slides into a channel on the side of the window frame and is secured in place by a screw. Part dimensions: approx 1/2" w X 1 3/16 h.