Abstract: The connector, in one embodiment thereof, rotatively receives a threaded coupling nut, and slidably receives an annular retainer. A spherical-keying arrangement prevents rotary movement between the retainer and body, and the retainer houses a pair of spring-loaded balls for forceably locking the coupling nut against rotation about the body. The coupling nut has an undulated radial surface which receives the balls to effect the rotation locking. The arrangement is so designed as to effect the locking with a substantially unvariably, resilient force, upon the coupling nut being rotatively threaded with and unthreaded from a mating coupling element.