although the invention is illustrated and described herein with reference to specific embodiments , the invention is not intended to be limited to the details shown . rather , various modifications may be made in the details within the scope and range of equivalents of the claims without departing from the invention . referring specifically to fig1 - 4 , there is shown a tubular graft 10 ( best seen in fig1 ) adapted to be secured to a stent 12 surrounding graft 10 in different ways ( as illustrated in fig2 a and 3 ). stent 12 includes a plurality of structural members , four of which are identified in fig2 b as 12 a , b , c , and d . fig4 is a cross - sectional expanded view of graft 10 illustrating an inner layer 14 of a non - porous material , and an outer layer 16 of knitted , woven , or braided material laminated to inner layer 14 . graft 10 further includes a plurality of fastening elements 18 ( only one of which is seen in fig4 ) adapted to be secured on an outer surface 20 of stent 12 surrounding graft 10 . an underside 22 of each fastening element 18 is fixed between inner layer 14 and outer layer 16 . a plurality of fastening elements 18 may be distributed lengthwise along the length of graft 10 , as shown in fig1 a , and 3 , and / or circumferentially about graft 10 ( not shown ). fastening elements 18 extend outwardly from outer layer 16 , as illustrated in fig4 . non - porous inner layer 14 reduces or minimizes the porosity of graft 10 , thus compensating for any such porosity in outer layer 16 . fastening elements 18 are retained between outer layer 16 , which is laminated to inner layer 14 , sealing underside 22 of each fastening element 18 between outer layer 16 and inner layer 14 . the finished assembly remains non - porous , resulting in a non - porous graft 10 . referring to fig2 a , the exemplary configuration illustrates graft 10 attached to an inside surface of stent 12 with fastening elements 18 projecting through stent 12 and a plurality of looped locking elements 24 , shown in greater detail in fig2 b , securing fastening elements 18 to stent 12 , thereby securing graft 10 to stent 12 . in this embodiment , each locking element 24 is knotted around both a fastening element 18 and an element or structural component of stent 12 to attach graft 10 to stent 12 . fig2 b is a detail view of a fastening element 18 secured to an element 12 a of stent 12 by a looped locking element 24 . alternatively , a particular fastening element 18 may be secured to any one or more of elements 12 b , 12 c , or 12 d of stent 12 by looped locking element 24 . as shown in fig2 b , fastening elements 18 may comprise d - shaped loops , the flat side of which is trapped between inner layer 14 and outer layer 16 , with the remainder of the loop projecting outwardly through outer layer 16 . similar to fig2 a , the exemplary configuration represented in fig3 illustrates graft 10 attached to an inside surface of stent 12 with fastening elements 18 projecting through stent 12 . however , instead of utilizing looped locking elements 24 as a means for securing fastening elements 18 to stent 12 , a linear locking element 26 may be looped through each fastening element 18 and secured to the stent 12 independently of its connection to the fastening elements 18 . more specifically , a linear locking element 26 may be threaded and looped through each fastening element 18 while remaining along an outside surface of stent 12 . the end points of linear locking element 26 are secured to stent 12 , thereby attaching graft 10 to stent 12 . alternatively , a linear locking element 26 may be threaded through ( not looped through ) fastening elements 18 and secured to stent 12 at at least two points along a length of stent 12 ( not shown ). in other words , a linear locking element 26 may be threaded through fastening elements 18 while remaining along an outside surface of stent 12 , with each end of linear locking element 26 knotted around an element 12 a , 12 b , 12 c , or 12 d of stent 12 to attach graft 10 to stent 12 . the shape of the fastening elements 18 is not limited to a d - shaped ring , as illustrated in fig4 . alternatively , fastening elements 18 may be round , square , triangular , or any other shape suitable for engagement with locking elements by which the graft 10 , through its fastening elements 18 , is secured to a stent 12 which surrounds it . a further embodiment of the present invention includes a plurality of fastening elements , which are an integral part of outer layer 16 , extending outwardly from outer layer 16 disposed along the length and / or circumference of outer layer 16 of tubular graft 10 . in other words , each fastening element is not a distinct component from outer layer 16 as illustrated in fig4 . instead , the fastening elements are part of the material of outer layer 16 , i . e ., loosely knitted , woven , or braided strands of material that form loops to act as fastening elements . at least some of the fastening elements are adapted to be secured on outer surface 20 of stent 12 surrounding graft 10 . the configurations of this embodiment with respect to means for securing the fastening elements to stent 12 ( i . e ., looped locking elements 24 or a linear locking element 26 ) are essentially the same as those of the embodiment of graft 10 comprising fastening elements 18 described previously herein with reference to fig1 - 3 . an exemplary material for forming inner layer 14 of graft 10 is expanded polytetrafluoroethylene . the present invention , however , is not limited to polytetrafluoroethylene , and may include any material that offers the desired non - porous property of inner layer 14 . the material of outer layer 16 may be a woven or knit polyester . the present invention , however , is not limited to polyester , and may include any knitted , woven , or braided material suitable for lamination to inner layer 14 . furthermore , the material of outer layer 16 is not limited to one that is porous , and may include any non - porous material suitable for lamination to inner layer 14 . fastening elements 18 and / or locking elements 26 may comprise conventional suture material . other materials may be used as well , however , and may comprise , for example , wire or plastic . one or both of the fastening element material and the locking element material may comprise , in whole or in part , a radiographically differentiable material . while preferred embodiments of the invention have been shown and described herein , it will be understood that such embodiments are provided by way of example only . numerous variations , changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention . accordingly , it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention .