An electro-pneumatic controller for use with a regulator. The electro-pneumatic controller includes a base having a body, a top surface, and a bore formed within the body. A locking mechanism is disposed within the bore of the body of the base, the locking mechanism having a top surface flush with the top surface of the base. A cover is coupled to the base and includes an open end with a rim, the rim contacting the top surface of the base and a portion of the top surface of the locking mechanism. The locking mechanism is rotated via a tool in a counter-clockwise direction after the cover contacts a portion of the top surface of the locking mechanism to lock the cover to the base.