Let-R-Balance combination ruler and postal scale
The metal combination ruler and postal letter scale has a slightly convex shape. From the hole at the shorter side hangs a clip (missing) to attach the letter for weighing. The four-point instructions describe how to use the scale. Various fixed fulcrum settings marked in ounces (one-four) indicate scale overhang positions. These settings also show corresponding postal rates for first-class and airmail valid from January 7, 1968, to May 15, 1971. The scale will remain in repose if the weight of the letter is within the given ounce setting and will tilt if weight exceeds the setting, thus necessitating a move to a higher mark. The top edge of the scale, also calibrated in inches (zero-nine), serves as ruler. The center of the scale’s face includes space for an advertising message.