Abstract: A stylet for use in guiding a catheter to a predetermined location within the body of a patient. The stylet may include a continuous core member for transmitting an electrical signal from a distal section of the stylet to a proximal end. In some embodiments, the stylet includes a differing stiffness profile along its length. A differing stiffness characteristics can be achieved by varying the number of strands of a wire, the diameter of each individual strand, twisting or braiding the strands, or varying the number of turns per unit length of the twisted strands. The stiffness of the stylet may decrease from the proximal end to the distal section, for example, intermittently, continuously, or along continuous sections adjacent the distal end. By using multiple strands bundled together, the beneficial conductive and, optionally, magnetic properties can be maximized while at the same time the stiffness characteristics can be modified.