the following detailed description should be read with reference to the drawings in which like elements in different drawing are numbered identically . the drawings , which are not necessarily to scale , depict selected embodiments and are not intended to limit the scope of the invention . examples of constructions , materials , dimensions , and manufacturing processes are provided for selected elements . all other elements employ that which is known to those skilled in the field of the invention . those skilled in the art will recognize that many of the examples provided have suitable alternatives that may also be used . turning now to fig1 . delivery system 15 includes tube 10 . tube 10 may be a micro - catheter , guide catheter , hypotube or any other type of tube commonly known in the art . depending on the application , the inner diameter or tube 10 may be 0 . 008 - 0 . 39 inches . tube 10 may be formed of a polymer or a combination of polymers , metal , a metal polymer composite , a combination of polymers and metallic braid ( not shown ). surrounding a distal portion of tube 10 is sheath 20 . sheath 20 may preferably be made of an elastomer or other highly compliant polymer . such polymers may include latex , styrenic block copolymers such as sbs and sebs made by shell under trade name of kraton , polyether - ester block copolymers ( cope ) for co - polyesters made by dupont under the trade name of hytrel , thermoplastic polyamide elastomers ( peba ) made by atochem under the trade name of pebax , and thermoplastic polyurethane elastomer ( tpur ) made by dow under the trade name pellathane , or thermoplastic polyolefin elastomers ( tpos ). sheath 20 may further include a proximal opening 25 and a distal opening 27 . in its non - distended configuration , sheath 20 may generally form a cylinder . sheath 20 may have a ridge ( not shown ) on its interior near distal opening 27 which may be configured to better capture the distal end of a prosthesis . in an alternative embodiment , sheath 20 my have slots or holes ( not shown ) which would enhance the porosity of sheath 20 and provide better flexibility . sheath 20 may be frictionally fit about the distal end of tube 10 . in a preferred embodiment , an adhesive bond 30 binds sheath 20 to tube 10 . sheath 20 may detach from tube 10 in a variety of ways . where sheath 20 is frictionally fit over tube 10 , detachment may be achieved simply by overcoming the frictional forces between sheath 20 and tube 10 , pushing a prosthesis out of the distal end of tube 10 . where sheath 20 is attached to tube 10 by adhesive bond 30 , the adhesive may be engineered to detach at any desired force . adhesive bond 30 may be formed with any medically approved adhesive . in an alternative embodiment , sheath 20 may have a circumferential perforation distal of adhesive bond 30 and thereby provide sheath 20 with a tear away detachment mechanism . turning now to fig3 . delivery system 15 is shown with a partially deployed self expanding coil 35 . coil 35 may be attached to pusher wire 40 . when pusher wire 40 is moved distally relative to tube 10 , the distal portion of coil 35 engages the distal portion of sheath 20 . sheath 20 then distends distally has coil 35 is advanced further out of tube 10 . once the entire coil 35 has been pushed out of tube 10 , pusher wire 40 may be electrolytically detached . methods of electrolytic detach are describe in u . s . pat . no . 5 , 122 , 136 which is hereby incorporated by reference . it may further be appreciated that a variety of detach mechanisms are available to serve this function and furthermore that pusher wire 40 does not need to be attached to coil 35 . fig4 depicts delivery system 15 in use in the vasculature . in this embodiment , a self - expanding stent 45 has been introduced into a blood vessel . pusher 40 has been advanced such that stent 45 was forced out of tube 10 and into contact with the interior of sheath 20 . after sheath 20 detached from tube 10 , sheath 20 remains in place about stent 45 and prevents any incursion by the surrounding tissue into the lumen of stent 45 and thereby maintains a patent fluid lumen for blood to flow through . another embodiment is depicted in fig5 where a tulip shaped coil 50 is placed in a body lumen . fig6 illustrates yet another embodiment where wire 55 is advanced through tube 10 . wire 55 may be formed of any suitable medically approved metal such as stainless steel or alloys of nickel such as nitinol . wire 55 has a pre - curved shape and is only forced out of that shape by placing wire 55 into tube 10 . care should be taken to choose a material for sheath 20 which will conform to the pre - curved shape of wire 55 without deforming wire 55 . as can readily be appreciated from fig7 , as wire 55 emerges from tube 10 it enters sheath 20 and resumes its pre - curved shape . in this embodiment , wire 55 is pre - curved into a flat disc - like shape but could be any of a variety of shapes known in the art . as described above , further advancement of wire 55 eventually detaches sheath 20 from tube 10 and thereby delivers pre - curved wire 55 into a desired location with sheath 20 surrounding wire 55 . fig8 depicts a particular use of pre - curved wire 55 . in this embodiment wire 55 forms into a disc - like shape suitable for covering an aneurysm neck . wire 55 may be delivered without any other structure being placed into aneurysm 60 . alternatively , wire 55 may be delivered after particles or other embolic materials ( not shown ) have been deployed into aneurysm 60 . in another embodiment wire 55 may be delivered into aneurysm 60 and particles may be delivered through wire 55 thereby filling aneurysm 60 and capping it with wire 55 . while the specification describes the preferred designs , materials , methods of manufacture and methods of use , those skilled in the art will appreciate the scope and spirit of the invention with reference to the appended claims .
an endoprosthesis cover may be attached to the distal end of a delivery device . the cover may be generally cylindrical in shape and may have a lumen through it . an endoprosthesis may then be covered as it is delivered to a treatment site .