This invention is an implantable vaso-occlusive device. It is typically a vaso-occlusive coil comprised of a primary helically wound coil which is then wound into a secondary shape. Central to the invention is the use of a stretch-resisting member fixedly attached within at least a portion of the primary coil. This stretch-resisting member is for the primary purpose of preventing stretching of the coil during movement of the coil e.g., by retrieval or repositioning after deployment. The device typically has a self-forming secondary shape made from a pre-formed primary linear helically wound, although it need not have the secondary form. Fibers may be introduced onto the device and affixed to the pre-formed linear member. The constituent member may be also be covered with a fibrous braid. The device is typically introduced through a catheter. The device is passed axially through the catheter sheath and assumes its form upon exiting the catheter without further action.