MIL-DTL-38999 Series II connectors are designed for harsh environments, with up to 128 contacts in an insert and a wide operating temperature range of -65 °C to 200 °C. These environmentally sealed connectors come in various configurations, including front and rear wall mount, jam nut, and box mount receptacles. Featuring thin walls and restricted lengths, they offer durability and reliability in military and aerospace applications. Available in 9 shell sizes and 52 insert arrangements, with gold-plated removable crimp contacts, they ensure secure connections. The aluminum shells can be plated with options like electroless nickel and cadmium olive drab, meeting RoHS compliance. With bayonet coupling and a service rating of I, these connectors are ideal for demanding environments that require high conductivity and ingress protection.