A multi-fiber fiber optic assembly comprising a receptacle and a plug that correspond and mate to optically connect a plurality of optical fibers. The receptacle comprises a receptacle housing, a receptacle multi-fiber ferrule and an excluding feature. The plug comprises a plug housing, a plug multi-fiber ferrule and a clearance opening for receiving the excluding feature therein. The receptacle and plug may further comprise at least one of a threaded coupling nut, a key for engaging a first key slot defined by the plug housing, a sleeve defining a second key slot for receiving the key therein, and a biasing spring.