This is a cover cap for window hinges. I'm not sure about the brand of the window or hinge. Probably “Roto”, as the other windows in my flat are Roto.

If you want to measure: The base plate of the hinge is 64 x 19.5 mm. The center part of the hinge is about 16mm high. The slot in the cover cap is 12mm wide.

There is no cover for the center part included. I never got the curvature and flexibility of that part right. I simple used a piece of white tape there.

Don't zoom in too close on my photos. The first layer came out horrible. But it doesn't matter, as nobody is looking too close on that part anyway.