Measure the height for the window opening.
Cut the tape to a length corresponding to the window opening and add 20 mm.
Unfold and remove the protective film at the end where you start.
Start attaching the tape to the frame but do not secure the upper corner to make it easier to fold it over towards the window reveal in the next step. Ensure it has an extra 10 mm at each end. Attach the strip 5-8 mm onto the frame.
Continue to apply the tape all the way down but wait with the bottom corner.
Fold the entire tape strip to the side and align it so that it fits into the corner.
Start peeling off the protective film while pressing it against the side.
Repeat the assembly on the other sides. Finish with even pressure over the entire back of the tape and in all angles.