MIL-DTL-38999 Series II connectors are designed for harsh environments, with up to 128 contacts in an insert and environmental sealing. Operating between -65 °C and 200 °C, these connectors come in various configurations including front and rear wall mount, jam nut, and box mount receptacles. Available in 9 shell sizes and 52 insert arrangements, they use M39029 rear release crimp contacts. Constructed with aluminum shells and offering plating options like cadmium and nickel, they ensure durability and reliability. With a bayonet coupling, gold contact plating, and a straight plug configuration, these connectors are ideal for military and aerospace applications requiring high performance in demanding conditions.