it would also be highly desirable to have the cylinder 50 as shown in fig4 expand radially outward to gently press outwardly onto the inner surface of the guiding catheter 40 to that end the cylinder 50 could be formed from a shape memory alloy such as nitinol to have a single product that would be suitable for 6 7 or 8 fr guiding catheters the outer diameter of the cylinder 50 should be approximately the inside diameter of an 8 fr guiding catheter such a cylinder 50 would then also fit snugly within either 6 fr or 7 fr guiding catheters the wall thickness for the cylinder 50 would ideally be between 0 001 and 0 003 inches fig5 is a highly enlarged cross section of an introducer 60 that would be used to place the self expandable cylinder 50 into the guiding catheter 40 the introducer 60 would have an outer diameter of its cylindrical portion 61 that was just smaller in diameter than the inner diameter of the 6 fr guiding catheter with the assistance of its tapered end 66 the introducer 60 could then be placed into a 6 7 or 8 fr guiding catheter to insert the ostial stent positioner 17 with the self expandable cylinder 50 into the introducer 60 the wire 11 attached to the strut.