What does the term "metric bolt" refer to?

The term "metric bolt" specifically denotes a bolt that conforms to the specifications outlined by the metric system for its diameter and thread pitch. This means that the measurements used for metric bolts are based on the International System of Units (SI), which utilizes millimeters to indicate the dimensions of the bolt’s diameter and the spacing of its threads.

For example, a metric bolt might have a diameter of 10 mm and a thread pitch of 1.5 mm, distinguishing it from standard bolts that might use inches and different thread specifications. This adherence to metric standards is crucial for compatibility in applications where precise measurements are required for fitting and assembly purposes. Understanding this allows engineers and technicians to ensure that they select the correct components for their projects, reducing the likelihood of mismatches in mechanical connections.

Other options might suggest characteristics that do not accurately define what makes a bolt "metric," as they focus on size variations, material composition, or unique designs, none of which are defining features of a metric bolt.