Antique calculator of the brand Brunsviga, type 20. The serial number is 12-31418. The length is ca. 40 cm, the height is 18 cm and the weight is 12.5 kilograms. The protective cover is missing. The device does work, but does need a bit of a cleanup. This calculator is used extensively in the 1950s and 1960s by the Administrative Department of a Dutch company. After 1970 the device along with other calculators in a glass case on display. This year they are in my possession, and the previous owner stated that they in working, good condition. Photos are part of the description. It is a so-called windmill calculator which is capable of performing the four basic mathematical operations with large figures performs: addition, subtraction, multiplication and Division. Who wants to know how the machine works, for example, can go to http://www.vintagecalculators.com/html/operating_a_pinwheel_calculato.html. Created by the Brunsviga Maschinenwerke A.G. in Braunschweig, not long after the second world war. The German Grimme, Natalis & Co from Braunschweig acquired licenses on the patents of Odhner in 1892 and produced calculators under the name Brunsviga. In 1927 the name of the company was changed to Brunsviga Maschinenwerke AG. In 1959 Brunsviga merged with Olympia.