An endovascular prosthesis comprising: a tubular body having a proximal end, a distal end, and a lumen disposed between the proximal and distal ends (106, 108), the tubular body including a body graft material and a plurality of stents coupled to the body graft material; a mobile external coupling including an extended configuration wherein the mobile external coupling extends outwardly from the tubular body, wherein the mobile external coupling is generally frustoconically shaped and includes a base coupled to the tubular body, a top spaced from the tubular body, and a coupling lumen disposed between the base and the top, wherein the coupling lumen is in flow communication with the body lumen and wherein the mobile external coupling includes a coupling graft material; and a coupling deployment device coupled to the mobile external coupling, wherein the coupling deployment device is also coupled to one of the plurality of stents coupled to the body graft material and wherein the coupling deployment device extends generally longitudinally along the mobile external coupling in the extended configuration, wherein the mobile external coupling and coupling deployment device include a collapsed configuration wherein the mobile external coupling and coupling deployment device are collapsed against the tubular body, and wherein the coupling deployment device is configured to store energy in the collapsed configuration such that when released from the collapsed configuration, the coupling deployment device provides an extension force to extend the mobile external coupling into the extended configuration. a tubular body having a proximal end, a distal end, and a lumen disposed between the proximal and distal ends (106, 108), the tubular body including a body graft material and a plurality of stents coupled to the body graft material; a mobile external coupling including an extended configuration wherein the mobile external coupling extends outwardly from the tubular body, wherein the mobile external coupling is generally frustoconically shaped and includes a base coupled to the tubular body, a top spaced from the tubular body, and a coupling lumen disposed between the base and the top, wherein the coupling lumen is in flow communication with the body lumen and wherein the mobile external coupling includes a coupling graft material; and a coupling deployment device coupled to the mobile external coupling, wherein the coupling deployment device is also coupled to one of the plurality of stents coupled to the body graft material and wherein the coupling deployment device extends generally longitudinally along the mobile external coupling in the extended configuration, wherein the mobile external coupling and coupling deployment device include a collapsed configuration wherein the mobile external coupling and coupling deployment device are collapsed against the tubular body, and wherein the coupling deployment device is configured to store energy in the collapsed configuration such that when released from the collapsed configuration, the coupling deployment device provides an extension force to extend the mobile external coupling into the extended configuration.