MIL-DTL-38999 Series I connectors feature up to 128 contacts in an environmentally sealed insert, designed for harsh environments with an operating temperature range of -65 °C to 200 °C. The connector family includes front wall mount, rear wall mount, and jam nut receptacles, as well as RFI grounding plugs, offering versatility in installation. With 9 shell sizes and 52 insert arrangements, these connectors utilize M39029 rear release crimp contacts, catering to various contact size needs. Constructed with high strength aluminum shells, they come in plating options such as cadmium and nickel, including RoHS compliant finishes. These circular receptacles, with a contact gender of female and a contact style of socket, are ideal for environment-resistant applications, with a service class rating of II and service class detail specifying box and through bulkhead mounting receptacle types.