What feature does a counterbore have?

A counterbore is a cylindrical recess that is cut into a material, typically to allow the head of a fastener to sit flush with or below the surface of the material. The distinctive characteristic of a counterbore is the presence of a pilot. This pilot is a smaller diameter cylindrical feature located at the center of the counterbore that helps guide the drill bit as it creates the larger cylindrical recess. This design ensures precision in the drilling process by keeping the drill bit aligned, which is crucial for achieving an accurate depth and diameter.

In contrast, while adjustable depth settings and feeding mechanisms can be features of drill presses and other machining equipment, they are not unique to counterbores themselves. A boring head, which is used to enlarge holes, is a tool that can modify the diameter of pre-existing holes, but it does not specifically define what a counterbore is. Therefore, the pilot is the key feature that defines a counterbore, making it the correct answer.