The MIL-DTL-38999 Series I connectors feature up to 128 contacts in an environmentally sealed insert, designed for harsh environments with an operating temperature range of -65 °C to 200 °C. Offering front wall mount, rear wall mount, and jam nut receptacles with RFI grounding plugs, they come in 9 shell sizes and 52 insert arrangements. Utilizing M39029 rear release crimp contacts in various sizes, including coax and twinax, these connectors are housed in high-strength aluminum shells with options for plating finishes such as light iridescent yellow cadmium, olive drab cadmium, electroless nickel, and black anodized aluminum. RoHS-certified cadmium-free finishes are also available. Suitable for military and industrial applications, they ensure reliable performance with a service rating of M and a mating life of 500 cycles. The connectors, with a contact gender of female and contact style of socket, provide conductive connectivity in demanding conditions, meeting environment-resistant standards for both box and through bulkhead mounting receptacles.