AERO
airmail letter scale

This letter scale was made by Philipp Jakob Maul from Hamburg in Germany. The letter scale is named Aero. The scale was intended for airmail, so for mail that was transported by plane or sometimes by helicopter. The enamel scale goes up to 50 grams. The scale is self-adjusting because the scale and the pointer rotate on the same axis. The scale is divided in three ways. Per half gram, below that stripes of measure per gram, and below that a block band with a division per five grams. The distribution per half gram and per gram is indicated on the left of the scale. To the right of the scale is the symbol for the CONCAV positioned scale, the designation MONOGRAD and the abbreviation D.R.G.M. that stands for Deutsches Reich GebrauchsMuster, a design protection that was cheaper and faster available compared to a patent. The height of the Aero is 155 millimeters. The diameter of the letter plate is 75 millimeters. A 100 grams version exists also. In a 1937 price list from the company G.C.T. Van Dorp & Co., based in the Dutch East Indies, this "AERO" is presented, see the image below.
Below some more pictures of the Aero letter scale for airmail.