Illustratively, the inner sleeve 18 and the outer sleeve 20 are made of silicone, PEBAX??? material, nylon, or other similar material- Any of the following methods or a combination could be used to fix nickel titanium tube 22 in the position shown in FIG. 2 between the inner and outer sleeves 18 and 20: heat shrink tubings, fusing inner and outer sleeves 18 and 20, dipping, coextrusion, enamel coa