MIL-DTL-38999 Series I connectors feature up to 128 contacts in an insert, designed for harsh environments with an operating temperature range of -65 °C to 200 °C. Available in front wall mount, rear wall mount, and jam nut receptacles, they offer RFI grounding options. With 9 shell sizes and 52 insert arrangements, these connectors use M39029 rear release crimp contacts in various sizes, including coax and twinax. Constructed with high strength aluminum shells, they come in plating options like light iridescent yellow cadmium, olive drab cadmium, electroless nickel, and black anodized aluminum, some RoHS certified. Ideal for military applications, these connectors ensure reliable performance with features like gold contact plating, N keyway polarization, and a mating life of 500 cycles.