MIL-DTL-38999 Series I connectors are designed for harsh environments, featuring up to 128 contacts in an insert. These circular connectors are front wall mount, rear wall mount, and jam nut receptacles with RFI grounding plugs, suitable for military specifications. Available in 9 shell sizes and 52 insert arrangements, they use M39029 rear release crimp contacts in various sizes. Constructed with high-strength aluminum shells, they offer plating options like light iridescent yellow cadmium, olive drab cadmium, electroless nickel, and black anodized aluminum, with RoHS-certified cadmium-free finishes. Operating temperatures range from -65 °C to 200 °C, making them ideal for demanding applications requiring reliability in extreme conditions.