Postamatic postal scale
This scale is a pen-shaped cylinder with an interior spring. The letter was attached to the clip at the bottom, and the scale was held upright so the spring would contract and indicate the rate. Rates for airmail and first-class postage valid between August 1, 1958, and January 6, 1963, appear on the scale's transparent green body. A silver clip is attached to the body of the scale so the user could carry the instrument around in a pocket, hence the name "The Pocket Postal Scale."
The original custom box for the Postamatic Pocket Postal Scale has a white bottom, silver interior, and a blue top. The inside of the box top contains instructions for using the scale and implores, “Why not present a Postamatic as a gift? Your Friends will find it useful too.”