D38999/20FC35PN is a MIL-DTL-38999 Series III subminiature connector designed for rugged, harsh environment applications in aerospace, defense, and marine industries. The connector features a threaded 360° turn coupling mechanism with environmentally sealed construction and is available in stainless steel, aluminum, or composite shell materials with multiple plating options including electroless nickel, nickel PTFE, black zinc-nickel, and olive drab cadmium. It supports up to 187 maximum signal contacts with standard contact sizes of 23, 22, 20, 16, 12, 10, and 8, accommodates shell sizes 9 through 25, and operates across a temperature range of -65°C to +200°C depending on shell finish. The connector offers multiple contact styles (crimp, solder cup/eyelet, and PCB tail), scoop-proof design, EMI control via spring fingers, and standard configurations including straight plugs with lanyard release and various receptacle mounting options (box mount, wall mount, jam nut, solder mount, weld mount, and through-hole bulkhead). With 500 mating cycles durability and hermetic and filter versions available, this connector is ideal for critical aerospace, defense, and marine systems requiring reliable, sealed connectivity in extreme conditions.