A fiber optic receptacle and plug assembly adapted to be mounted within an opening through a wall of a connection terminal. The receptacle and plug define complimentary alignment and keying features for ensuring that the plug is mated with the receptacle in a predetermined orientation. An alignment sleeve is disposed within the plug for receiving a multi-fiber receptacle ferrule and a multi-fiber plug ferrule. The fiber optic receptacle and corresponding plug each include a biasing member assembly for urging the receptacle ferrule and the plug ferrule towards one another, wherein the biasing member assembly includes a round spring, a spring centering cuff and a ferrule boot that operatively engage the rear of the receptacle ferrule and the plug ferrule, respectively, to substantially center a spring biasing force on the end face of the receptacle ferrule and the plug ferrule.