Is millradion or mills part of the metric system?

Milliradian (mrad) and mill are not part of the metric system, but they are used in specific fields. The milliradian is a unit of angular measurement commonly used in optics and military applications, while the mill (1/1000 of an inch) is often used in machining and engineering. The metric system primarily uses units like meters, liters, and grams for measuring length, volume, and mass, respectively.