Plastic guide on 4 x 4 Al window

Question

Part number need for item pictured. I did not get measurements, but 1/2" or less.

Paul · Accepted Answer

I'm afraid I don't recognize this roller. Could you remove it from the window and show us a picture of it out? I would also like its width, height, the and thickness of the housing, as well as the diameter and thickness of the wheel. Thanks!