an improved stent - graft device is provided that delivers a smooth flow surface over a range of operative expanded diameters by applying a unique cover material to the stent through a technique that allows the cover to become wrinkle - free prior to reaching fully deployed diameter . the unique cover material then allows the device to continue to expand to a fully deployed diameter while maintaining a smooth and coherent flow surface throughout this additional expansion . employed with a self - expanding device , when the device is unconstrained from a compacted diameter it will self - expand up to a fully deployed diameter with the graft being substantially wrinkle - free over diameters ranging from about 30 - 50 % to 100 % of the fully deployed diameter . preferably , the graft component comprises an elastomeric material , such as silicone , polyurethane , or a copolymer of pave - tfe .