The MIL-DTL-38999 Series I connectors feature up to 128 contacts housed in an environmentally sealed insert, designed for extreme operating temperatures ranging from -65 °C to 200 °C. This harsh environment connector family offers front wall mount, rear wall mount, and jam nut receptacles, as well as 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, the connectors come with a range of plating choices such as cadmium-free finishes. Meeting military specification MIL-DTL-38999 I, these circular receptacles ensure reliable performance in demanding applications.