The D38999/20WB99PA is a wall mount receptacle connector conforming to MIL-DTL-38999 Series III specification, featuring an aluminum shell with olive drab cadmium over electroless nickel base finish. This connector utilizes a triple-start threaded coupling with self-locking acme threads, crimp removable rear-release contacts, and scoop-proof design for enhanced durability and shock resistance. The connector is available in 9 shell sizes (A through J) with multiple insert arrangements supporting M39029 contacts in sizes 22D, 20, 16, 12, 10 power, and 8 twinax. It incorporates a master keyway with four minor keyways for polarization control and is designed for both general-purpose and severe environment applications in aerospace, military, and industrial systems where reliable high-performance cylindrical connectors are required.