The term “mil-spec” is short for military specification, which is a set of standards that specifies the requirements for products used by the U.S. military. The mil-spec standards are often more stringent than commercial standards, and they’re usually reserved for products that will be used in mission-critical applications. Some examples of mil-spec products include aircraft parts, medical devices, and communication equipment.
Military specifications are usually developed by the military themselves, but sometimes they’re developed by private companies or organizations that have been contracted by the military. There are a wide variety of mil-spec standards, covering everything from the materials used in a product to the way it’s manufactured.