This early mechanical calculator was made by the RC Allen Adding Machine Co. in 1938 (based on the serial number 831129). It's the model 66 with a 5-digit display. The paper tape guide and holder are complete and intact (often missing in these old machines), and the ribbon is in place under the cover. It's a little dry though it does still print. This model is manual with a crank handle, not electric.

The body is black enameled steel, the key plate is green steel, and the keys are white, black, and red Bakelite. There are alphabetical keys too. I'm not sure how to make the machine add and print though - when I press the keys, the crank won't operate but when they're cleared it pulls fine. It obviously needs a little maintenance. The machine is clean and in very good cosmetic condition.