A bore gauge is a precision measuring tool used to determine the internal diameter of a hole or cylinder. It typically consists of a set of calibrated rods or a dial indicator that can be adjusted to fit the bore's size. Bore gauges are essential in manufacturing and engineering to ensure that parts meet specific tolerances and specifications. These tools come in various types, including dial bore gauges and digital bore gauges, each offering different features for accuracy and ease of use. Proper use of a bore gauge helps maintain quality control in processes involving machining and assembly.