Dial bore gages are primarily used to measure:

Dial bore gages are specifically designed for measuring the internal diameter of cylindrical openings, which are best described as holes. This tool allows for accurate measurement of the size and condition of the bore, which is crucial in various machining and manufacturing applications. By using a dial indicator attached to a precision gauge, operators can determine the diameter at different points within the hole, identifying any imperfections or variations.

The functionality of dial bore gages is particularly important in ensuring that components fit together properly, which can affect the performance and safety of mechanical assemblies. Other measurement tools would be more suitable for assessing grooves, surface finishes, or radii, as their designs and measurements cater to those specific features rather than the internal dimensions of holes.