Phifer SunScreen - is a woven fiberglass product. The unique ribbed weave is designed to block up to 70% of the sun's heat and glare. SunScreen stops insects but will allow gentle breezes to enter. If your windows have existing insect screens, SunScreen can be installed in the same manner, often using the same frames. SunScreen offers good outward visibility and adds daytime privacy to your windows. Unlike films or glass coatings, SunScreen stops the sun's heat and glare before it hits your windows and sliding glass doors. It's like having a shade tree in front of your window without blocking the view. Exterior shading is the most effective way to block solar heat gain.