Which tool is typically used for measuring internal dimensions?

The tool primarily utilized for measuring internal dimensions is inside calipers. This instrument is specifically designed to measure the distance between two points inside an object, such as the diameter of a hole or the width of a groove. The design of inside calipers allows for the user to insert the pointed ends into the internal area to get a precise measurement of the internal dimensions.

The other tools mentioned serve different purposes: the vernier caliper can measure both external and internal dimensions but is more commonly associated with external measurements due to its versatility. The outside micrometer is designed for measuring the exterior dimensions of objects with high precision, while a depth gauge is used to measure the depth of holes or recesses. Each tool has its specific application, making inside calipers the correct choice for accurately measuring internal dimensions.