Abstract: An electrical connector system is provided, of the type that includes housings of plastic-metal hybrid construction, which provides good moisture-tight sealing between the plastic shells and metal inserts and around grounding springs. The receptacle connector has a front edge to which the plastic shell and metal insert extend, and the plug connector includes a ring-shaped elastomeric first seal (90, FIG. 3) that is compressed by the front edge of the receptacle shell and insert (96, 98), to not only seal the inside of the mating regions of the connector but also to seal any slight gap (100) between the plastic shell and metal insert of the receptacle. The forward edge of the plug presses against a second elastomeric seal (92) which is on the receptacle, with the first and second seals sealing a region containing a grounding spring (80) that electrically connects the inserts of the plug and receptacle.