The term "5.5 mm" refers to a measurement of length, specifically 5.5 millimeters. A millimeter is a unit in the metric system, which is commonly used around the world for precise measurements. To put it in perspective, 5.5 mm is slightly more than 0.2 inches, making it a small but significant measurement often used in fields like engineering, manufacturing, and medicine. In practical applications, 5.5 mm can describe the diameter of small objects, such as screws or drill bits. It is also relevant in the context of camera lenses, where a 5.5 mm focal length can produce wide-angle images. Understanding this measurement is essential for tasks requiring accuracy and precision.