A cross-wall indicator post is provided to control through a wall, open and closed configurations of a piping system control valve having a manual actuator with a valve-hand wheel. The indicator post includes a post body having a mounting flange to mount the post body to a wall separating the post body from the control valve. An operating stem extends through the post body and is adjustably, slidably, non-rotatably, telescopingly engaged with an extension rod. A post-hand wheel is engaged with the operating stem for rotation thereof. An engagement member is fixedly attached to the extension rod, configured to be selectively, mechanically engageable with, and releasable from, the valve-hand wheel to actuate the control valve between the open and closed configurations thereof. Rotation of the post-hand wheel rotates the operating stem, the extension rod, and the engagement member, to, in turn, rotate the valve-hand wheel.