A manual projector screen with dimensions of 145 x 145 cm (57 x 57 inches) is a type of projection screen that can be manually pulled down and retracted when needed. It provides a flat and smooth surface for projecting images and videos from a projector onto, making it a popular choice for home theaters, classrooms, boardrooms, and conference rooms. Here’s a description of a typical manual projector screen of this size:

1. Screen Size: The screen has a square aspect ratio with a total diagonal size of 145 cm (57 inches). This size is suitable for displaying a variety of content, including movies, presentations, and slideshows.
2. Manual Pull-Down Mechanism: The screen is operated manually by pulling it down from a cylindrical housing mounted on the wall or ceiling. When not in use, it can be retracted back into the housing to save space and protect the screen.
3. Screen Material: The screen material is usually matte white or a similar neutral color to provide a uniform and high-contrast surface for projection. Matte surfaces reduce glare and reflection for better image quality.
4. Aspect Ratio: As a square screen, it often has an aspect ratio of 1:1, which means it can display both standard 4:3 and widescreen 16:9 content with black bars on the top and bottom or sides, depending on the content’s aspect ratio.
5. Viewing Angle: The screen material typically has a wide viewing angle, allowing the audience to view the projected content clearly from various positions within the room.
6. Mounting Options: The housing of the screen can be mounted on the wall or ceiling using brackets or hardware provided with the screen. Some screens also offer adjustable mounting options to accommodate different installation preferences.
7. Screen Tensioning: Some high-quality manual projector screens feature a tensioning system to keep the screen flat and wrinkle-free, ensuring a smooth and distortion-free image.
8. Black Borders: Many manual screens have black borders around the viewing area, enhancing the perceived image contrast and providing a professional look.
9. Ease of Use: Manual projector screens are simple to operate and do not require any electrical connections or remote control. They are typically pulled down and locked into position using a pull cord or handle and retracted by releasing a locking mechanism.
10. Versatile Use: These screens are suitable for a wide range of applications, including home entertainment, business presentations, educational purposes, and more.
11. Maintenance: Manual projector screens are relatively low-maintenance, requiring occasional cleaning to remove dust or smudges from the screen surface.
12. Portability: Unlike fixed screens, manual screens are portable and can be easily moved or relocated if needed.

It’s important to note that specific features and specifications may vary depending on the brand and model of the manual projector screen. When purchasing a manual screen, consider factors such as screen material quality, gain, and the room’s lighting conditions to ensure it meets your specific projection needs.