These fully assembled screens are constructed of white aluminum frame, plastic corners and glide brackets with gray fiberglass mesh. For aesthetic purposes, some only use these screens seasonally, as they prefer to not have permanently affixed screens on their windows. These screens are used horizontally with vertical sliding windows, and vertically on horizontal sliding windows. When using these expandable screens horizontally, the width can adjust from 20-1/8 inch to 37-3/16 inch, with a fixed height of 18-3/16 inch. When using the screens vertically, the net width is 18-3/16 inch, and the height can adjust from 20-1/8 inch tall to 37-3/16 inch. These screens are easy to install and are commonly used as temporary screening when exterior temperatures allow. These screens are used to help block out flying and crawling insects when ventilation through open windows is desired.