MIL-DTL-38999 Series I connectors feature up to 128 contacts in an insert, offering environmental sealing and a wide operating temperature range of -65 °C to 200 °C. This harsh environment connector family includes front wall mount, rear wall mount, and jam nut receptacles, along with RFI grounding plugs. With 9 shell sizes and 52 insert arrangements available, they utilize M39029 rear release crimp contacts in various sizes, including coax and twinax options. Constructed with high-strength aluminum shells, these connectors come in different plating options such as light iridescent yellow cadmium, olive drab cadmium, electroless nickel, and black anodized aluminum, some of which are RoHS certified. Suitable for military and industrial applications, they ensure reliable performance with a maximum operating temperature of 175 °C and a minimum of -65 °C, making them ideal for demanding environments.