MIL-DTL-38999 Series II connectors feature up to 128 contacts in an environmentally sealed insert, suitable for harsh environments with an operating temperature range of -65 °C to 200 °C. These thin-walled connectors come in various mounting options including front and rear wall mount, jam nut, and box mount receptacles. Available in 9 shell sizes and 52 insert arrangements, they utilize M39029 rear release crimp contacts in sizes 22D, 22M, 22, 20, 16, and 12. Constructed with aluminum shells, they offer plating options such as light iridescent yellow cadmium, olive drab cadmium, electroless nickel, and black anodized aluminum, including RoHS certified cadmium-free finishes. Ideal for military and industrial applications, these connectors provide reliable performance with gold-plated contacts, bayonet coupling, and a service rating of M for environment-resistant box and through bulkhead mounting receptacles.