A stent graft prosthesis includes a fabric sleeve supported by a series of ring stents, including ring stents having a saddle shape with peaks and valleys, the axial alignment of equivalently shaped ring stents in the series of ring stents being such that with respect to at least one shaped ring stent other shaped ring stents are angularly offset. Multiple series of ring stents may be interposed such that at least one ring stent in a first series of ring stents S1-Sn is located between two ring stents in at least one other series of ring stents So1-Son, the angular offset of ring stents in the first series S1-Sn being different from the angular offset of ring stents in at least one other series of ring stents (So1-Son). The offset changes the amount of fabric surface between peripheral contact points of successive shaped ring stents.
