Abstract: An endovascular device (10) for insertion into a bodily vessel (5) to treat a diseased, damaged or weakened portion of a vessel wall (50), the endovascular device (10) comprising: a mechanically expandable device (11) expandable from a first position to a second position, said mechanically expandable device (11) is expanded radially outwardly to the second position such that the circumferential surface of said mechanically expandable device (11) engages with the inner surface of the vessel (5) so as to maintain a fluid pathway through said vessel (5); and a membrane (20) covering at least a portion of the circumferential surface of said mechanically expandable device (11), the membrane (20) comprising a plurality of pores (25), the porosity of the membrane (20) being defined by the ratio of the material surface area of the membrane (20) determined by the size of the pores (21) and the distance between adjacent pores (22, 23); wherein the mechanically expandable device (10) is positioned in the bodily vessel (