Rc2n - Window fittings on the ground floor

the mushroom heads about every 50cm and the counterparts on the frame as well, 3-layer glazing, then it should be RC2N

Here you can see the difference. You should have the image on the left on the upper floor and then the middle one on the ground floor. The N refers to the type of glass used.

Here are pictures of the windows:
1. Height 113 cm, width 100 cm, 2 mushroom caps and 2 frame fastenings (3 pictures)
2. Height 128 cm, width 100 cm, 2 mushroom caps and 3 frame fastenings. (1 picture)