Cat 5 Screens are made from a woven fabric consisting of polypropylene threads. The threads are combined in a basket weave to form the fabric. The weave has approximately 5% open space. This open space allows light to get through the fabric lighting the room behind the screen and providing visibility to the outside. This open space also allows small amounts of air and moisture to move through the fabric.
This homeowner is using flush-mount to secure his window areas. The inconspicuous anchors along the sides of the window are barely noticeable closeup and not at all noticable at a distance.
Implications of flush-mounting a flexible fabric screen over windows and doors that contain breakable glass:
The screen stops heavy flying debris but flexes during the process. Depending on the size of the opening and the force of the object the flex in a category 5 hurricane could be from a few inches for a narrow span to nearly 20 inches for a 10 ft span. If the glass of a window or door is within the flex range it could be broken.
If the glass breaks, the screen preserves the envelope of the building. The approximately 95% closure of the weave allows a small amount of air through but stops the damaging surges of wind which could blow out the walls or lift the roof. When raining, mist may enter but the screen prevents the catastrophic flooding that could otherwise occur.