The first machines were built according to W. Odhner's 1890 design, and were distributed under the brand name "Brunsviga". The machine for sale is a Brunsviga 13 ZK model which were manufactured from 1929.
But the exact age of this example is not known. Machine can add, subtract, multiply and divide for which instructions can be found online. I did not clean it since I know collectors like to do that themselves. The item "Brunsviga 13 ZK mechanical calculator" is in sale since Monday, September 4, 2017. This item is in the category "Antiques\Science/Medicine\Scientific Instruments".
The seller is "tvrtko2004" and is located in Reading. This item can't be shipped, the buyer must pick up the item.