Adjustable & Versatile: The adjustable window screen size is 21 x 15 x 0.7 inches when closed, and expands to 40 x 15 x 0.7 inches to fit different window sizes. It can be flipped 90° for vertical window use, ensuring flexibility for your entire home Easy Installation: Install in just 3 simple steps with no professional tools required. One person can quickly install or detach the expandable window screen, making cleaning and moving easier while saving on repurchasing costs High Transparency Mesh Screen: Made of flame-retardant fiberglass mesh, this durable expandable screen for windows effectively blocks critters while remaining nearly invisible. It allows natural light to enter, combining functionality and appeal Rust-Proof Tracks: The heavy-duty metal tracks are not easy to rust even in humid environments. Reinforced for added strength, they provide smooth sliding with frequent use and strong pressure durability, ensuring long-lasting use Felt Edges for Better Seal: The felt edges on the top and bottom seal gaps around the window frame, keeping out unwanted critters. This design keeps water out during heavy rain, enhancing the retractable window screen's overall sealing performance