1. The smallest clear window opening size A x B
width x height

2. Width: A the distance from the rabbet to the rabbet of the smallest clear window opening size.

3. Height : B the distance from the rabbet to the drip cap, as demonstrated in the drawing.

4.Rabbet thickness: C as demonstrated in the drawing.

5. Window manufacturer - Włoszczowa, Sokólka, Vidok etc.