The Upper Window Liner(s) are located at the top of the raamframes. The Middle Window Liner(s) are located in the middle of the side windows and are at an angle to the upright position.

Like the other window liners, these liners are also made out of styrofoam.
Not the gross white styrofoam that we know of packaging, and styrofoam with a high density and very fine grain.

The expanded polystyrene is in the right shape, cut out and then treated with Acrylic One (hard plaster) and one low shipping to most european countries.
Then it's time to make everything smooth, to sand and to work with additional filler if needed.

The final finish is the application of a primer and gray paint.

Extensive info and images can be found on following link:
https://www.flightdeck737.be/hardware/platform/window-liners/side-aft-upper-window-liners-capt-en-fo/

Translated by Yandex.Translate and Global Translator