Mil-Spec (abbreviation for Military Specification) refers to the US Department of Defense military standard. Only when a product meets these highest standards of sourcing, manufacturing, materials, quality and delivery can it be called a MIL-SPEC-inspired product or component. A real seal of quality. The Luminox 3350 Series watch is built to the MIL-PRF-46374G performance specification standard. This means that their water resistance, robustness and overall quality reflect US Department of Defense standards.