The MIL-DTL-38999 Series I connectors feature up to 128 contacts in an insert, designed for harsh environments with a wide operating temperature range from -65 °C to 200 °C. These connectors come in various mounting options including front wall mount, rear wall mount, and jam nut receptacles, all offering RFI grounding plugs. With 9 shell sizes and 52 insert arrangements, they accommodate M39029 rear release crimp contacts in sizes 22D, 22M, 22, 20, 16, and 8. Constructed with high strength aluminum shells, they offer plating options such as light iridescent yellow cadmium, olive drab cadmium, electroless nickel, and black anodized aluminum, with RoHS-certified cadmium-free finishes available. Suitable for military and industrial applications, these circular connectors provide reliable performance with a mating life of 500 cycles and conductivity in an environment-resistant design.