MIL-DTL-38999 III (D38999) harsh environment connectors feature wall mount receptacles, jam nut receptacles, and straight self-locking RFI plugs. Available in 9 shell sizes and 54 insert arrangements, they utilize M39029 contacts in various sizes, including 22D, 20, 16, 12, 10 power, and 8 twinax. These connectors come in aluminum, stainless steel, or lightweight composite shells with plating options like olive drab cadmium, nickel, black zinc nickel, and passivated stainless steel, meeting RoHS and Boeing BACC standards. Designed for military applications, they offer reliable performance in extreme conditions with operating temperatures ranging from -65°C to 200°C, making them ideal for demanding environments.