The Curta calculator, the first hand held calculator.
The Curta was invented by Curt Herzstark while he was a prisoner in the Buchenwald concentration camp. Following the end of WWII he completed and perfected the design. They were made in Liechtenstein by Contina AG Mauren. They were widely considered the best portable calculators available, until they were displaced by electronic calculators in the 1970s.
these are still being sold today, look on ebay.