Measure Before You Order: For a seamless installtation, please measure your window opening. For Inside Mount: Ensure your ordered roller shade width is 0.2 - 0.5" shorter than your window opening.(REQUIRED 3" WINDOW DEPTH) For Outside Mount: Ensure your ordered roller shade width is 3-6" longer than your window opening Convenient Operation: The pull down blackout shades with free-stop and auto retract design makes operation exceptionally simple and quick. Whether it's opening in the morning to welcome the first ray of sunshine or closing at night to enjoy a peaceful evening, it’s easily done with just one pull-down Silent Raise and Lower Technology: A meticulously designed internal mechanical structure ensures smooth and quiet operation when raising and lowering the roller window shades, ensuring that adjustments at night do not disturb your family's sleep Superior Light-Blocking Performance: Utilizes high-composite fabric with a special blackout layer that can effectively block over 99% of UV rays, room darkening instantly upon pulling. This blackout blinds protects your privacy and prevents indoor furniture from damage due to prolonged exposure to sunlight Sustainable Green Fabric: Cordless window shades selected high-quality fabric that is not only safe and odorless, harmless but also soft to the touch. It offers excellent breathability and heat insulation, bringing more comfort and peace of mind to your home life Safe Cordless Design and Sturdy Bottom Rail: Discards traditional cords and adopts a safe and reliable pull-down control method, avoiding potential safety hazards. The bottom rail is made of sturdy aluminum alloy, enhancing overall stability and preventing the roller shades from swaying or tilting High-Quality Aluminum Alloy Valance: Each set of roller blinds comes with a valance that has been wrapped in fabric to match the color of the window shades fabric, enhancing the overall aesthetics and harmony. It adds a warm and elegant touch to living rooms, bedrooms, kitchens, home theaters, and home offices High-Quality Built-in Spring System: Our cordless blinds equipped with long-lasting stainless steel springs, which have undergone 20,000 rigorous tests, ensuring excellent rebound performance even after prolonged frequent use. This reduces the frequency of maintenance If you find any missing parts in the package, or have any questions during installation or about the size you ordered, please feel free to contact us and we will respond promptly Cordless Blackout Roller Shades for Windows