D38999/26WD18SN is a MIL-DTL-38999 Series III self-locking RFI grounding plug connector designed for military and aerospace applications. It features an aluminum shell with olive drab cadmium over electroless nickel base finish, shell size D, and insert arrangement 18 with socket contacts. The connector utilizes normal (N) polarization keying for proper mating alignment. This connector is suitable for demanding environments requiring reliable electrical connections with RFI grounding capabilities, commonly used in military equipment, aerospace systems, and other high-reliability applications.