Abstract: A protective cover for a multiple pin type electrical connector receptacle having an insert shell provided with a plurality of locking keys spaced about the circumference of the shell to receive mating, locking lands on the cover, is disclosed wherein the cover is provided with an additional antirotational locking means between the cover and shell for preventing unintentional release rotation of the cover relative the shell when they are in an assembled relation. The exemplary embodiment of antirotational locking means includes the provision of a spring detent means mounted within the cover wherein a generally V-shaped detent is spring mounted as part of an integral, one piece contoured spring metal plate to cooperate with an orienting key on the shell to prevent unintentional release of the cover from the shell due to the resiliency of the detent engaging over the orienting key when the cover is rotated into its fully assembled position relative the shell.