A coil device is provided with a stretch resistant feature. The device includes a wound coil defining a lumen and a stretch resistant member at least partially received within the lumen. A headpiece is formed by a joining of the coil and a restrictor member, typically by plasma welding. The restrictor member is also at least partially received within the lumen and defines an aperture adapted to movably receive a portion of the stretch resistant member to allow the wound coil to stretch and elongate. The stretch resistant member includes an enlarged portion that is larger than the aperture and adapted to engage the restrictor member to prevent or resist stretching of the wound coil. The restrictor member may be provided as a separate element fixedly secured to the coil wire, or the coil wire may include one or more minor turns adapted to perform the function of the restrictor member.