A coupler/coupling ring assembly, comprising: a coupler, including: a body portion having integral first and second ends (103-1, 103-2) and an integral gate having a key entry region consisting of a space between opposing, disconnected distal ends of the gate, wherein the body portion has a free space at least partially enclosed by an inner surface of the body portion and the gate; and a coupling ring that is removably engageable with the coupler, the coupling ring including: an integral perimetral body having a head section, a foot section, and two arm sections therebetween, wherein at least one of the arm sections has a key region that is complimentary to the gate, further wherein the key region consists of a solid, integral portion of the at least one arm section, wherein the coupler/coupling ring assembly is characterised in that the head section has an interior curvature, C, and the foot section has an opposing interior curvature, c, where c> C, and wherein the coupling ring further comprises: a crossbar integrally connecting the two arm sections, disposed between the key region and the foot section or at least one nub that protrudes inwardly from an inner surface of the perimetral body of the coupling ring, disposed between the key region and the foot section. a coupler, including: a body portion having integral first and second ends (103-1, 103-2) and an integral gate having a key entry region consisting of a space between opposing, disconnected distal ends of the gate, wherein the body portion has a free space at least partially enclosed by an inner surface of the body portion and the gate; and a coupling ring that is removably engageable with the coupler, the coupling ring including: an integral perimetral body having a head section, a foot section, and two arm sections therebetween, wherein at least one of the arm sections has a key region that is complimentary to the gate, further wherein the key region consists of a solid, integral portion of the at least one arm section, wherein the coupler/coupling ring assembly is characterised in that the head section has an interior curvature, C, and the foot section has an opposing interior curvature, c, where c> C, and wherein the coupling ring further comprises: a crossbar integrally connecting the two arm sections, disposed between the key region and the foot section or at least one nub that protrudes inwardly from an inner surface of the perimetral body of the coupling ring, disposed between the key region and the foot section. an integral perimetral body having a head section, a foot section, and two arm sections therebetween, wherein at least one of the arm sections has a key region that is complimentary to the gate, further wherein the key region consists of a solid, integral portion of the at least one arm section, wherein the coupler/coupling ring assembly is characterised in that the head section has an interior curvature, C, and the foot section has an opposing interior curvature, c, where c> C, and wherein the coupling ring further comprises: a crossbar integrally connecting the two arm sections, disposed between the key region and the foot section or at least one nub that protrudes inwardly from an inner surface of the perimetral body of the coupling ring, disposed between the key region and the foot section.