An electro-pneumatic controller includes a base portion having at least one lateral surface and a plurality of passageways disposed through the base portion. A bore extends through the lateral surface, and the bore has a counterbore portion and a threaded engagement portion. A standard NPT plug may be coupled to the base portion, and the plug has a head portion and an engagement portion that threadedly engages the engagement portion of the bore. A top surface of the head portion of the plug is coplanar with the lateral surface of the base portion or is disposed within the counterbore portion of the bore.