The MIL-DTL-38999 Series I connectors are designed for harsh environments, featuring up to 128 contacts in an insert with environmental sealing. Operating between -65 °C and 200 °C, these connectors come in various configurations including front wall mount, rear wall mount, and jam nut receptacles, along with RFI grounding plugs. With 9 shell sizes and 52 insert arrangements, they use M39029 rear release crimp contacts in sizes 22D, 22M, 22, 20, 16, and 8, including coax and twinax options. Constructed with high-strength aluminum shells, they offer plating choices like light iridescent yellow cadmium, olive drab cadmium, electroless nickel, and black anodized aluminum, with RoHS-certified cadmium-free finishes available. Ideal for military and other rugged applications, these connectors provide reliable performance in demanding conditions.