A ball-bearing mechanical stage is a laboratory instrument used in microscopy to hold and move specimens on a microscope slide. It is similar to a regular mechanical stage, but instead of using gears or other types of mechanical controls, it uses ball bearings to move the slide in two perpendicular directions.

This allows for smoother and more precise movement of the specimen under the microscope objective for examination and analysis. The ball-bearing mechanical stage typically includes a vernier scale or other measuring device to aid in accurate placement of the specimen.

It is commonly used in research and clinical laboratories for a variety of applications, including histology, pathology, and microbiology. The ball-bearing mechanical stage is especially useful for high-magnification microscopy, where even slight movements can affect the clarity and focus of the image.