Furthermore, to protect against outside elements such as humidity, metal cased actuators have been developed. If moisture ingresses into the device, it can cause nickel migration to happen, which often leads to dielectric breakdown, especially in regions where high stress fatigue occurs. By packaging the standard resin-coated actuator into a hermetic sealed case, humidity and other particulates will no longer be able to negatively impact the actuator. In addition, the inclusion of inert gas into the device also prevents moisture from entering via the terminations. As a result, long operational life and high performance have been attained. To complete this original design, a pre-load structure and a flange structure have been added to ease the assembly process.