The 776533-4 is an AMPSEAL 16 12-way plug connector featuring a D key configuration with black housing and green polycarbonate locking ring (PLR) for keyed mating. This connector is designed with a reduced diameter seal to provide environmental sealing in harsh industrial and transportation applications. The 1.58 mm contact size accommodates standard automotive and industrial wiring, and the connector includes integrated wedge/TPA (Tertiary Positioning Aid) for secure contact retention. The reduced diameter seal variant offers improved sealing performance in compact installation spaces while maintaining the environmental protection required for outdoor and underhood automotive environments. This connector is commonly used in engine control modules, transmission systems, and other sealed electrical assemblies in commercial vehicles and industrial equipment.