Abstract: An appliance for a room door serves to display a message at both the inside and outside faces of the door and further enables one at the inside face to observe individuals and activities beyond the outside face. The appliance includes an interior unit against the inside face of the door, an exterior unit against the outside face of the door, an operating shaft extending through the door and between the two units, and a viewer that extends through the operating shaft and clamps the units against their respective faces of the door. Each unit has a cover provided with a window and a message wheel, a portion of which is exposed for viewing through the window in its cover. The message wheels are engaged with the operating shaft, so that they rotate in unison and display like messages through the windows in the covers of their respective units.