MIL-DTL-38999 Series II connectors are designed for harsh environments, featuring up to 128 contacts in an insert with environmental sealing. Operating between -65 °C and 200 °C, these connectors offer versatility with various mounting options such as front wall mount, rear wall mount, jam nut, rear box mount, and front box mount receptacles. Available in 9 shell sizes and 52 insert arrangements, they use M39029 rear release crimp contacts in sizes 22D, 22M, 22, 20, 16, and 12. Constructed with aluminum shells, they come in plating options like light iridescent yellow cadmium, olive drab cadmium, electroless nickel, and black anodized aluminum, with RoHS-certified cadmium-free finishes. The MS27473 model specifically, with 55 gold-plated contacts, offers reliable electrical connections in demanding military and industrial applications, ensuring durability with a service rating of M and a mating life of 500 cycles. The connectors, meeting MIL-DTL-38999 II specifications, provide secure and conductive connectivity, ideal for environment-resistant Box and Through Bulkhead Mounting Receptacle Types.