Vessel occlusion coils disclosed that have a primary configuration for delivery and a secondary configuration for deployment that is conferred upon the devices by a stretch resistant member. In the secondary configuration, the stretch resistant member forms a stiffer coil and may have a greater diameter, and a more complex shape having some interior space, at one end than at the other end, for improved anchoring of the device in the vessel. The methods include intravascular delivery and deployment for implanting one or more vessel occlusion devices.
