This compass is a well made compass with some age related issues but still works great. Serial number is 12742. This U.S. Engineer Corps compass was manufactured by Plan, Ltd. Neuchatel Switzerland. These compasses represent an early (circa WWI) attempt at a mirror compass, with an (originally) polished brass insert in the cover which allows the card (w/ bearings printed in reverse) to be read while sighting on a target. The bottom of the case is stamped with Plan Ltd. Neuchatel Switzerland and the serial number. WW1 era made by Plan LTD Neuchatel Switzerland for the US Engineer Corps for the US Army. Made of solid brass with two knobs one lock the bezel ring that rotates after you unlock it the other locks the compass rose when you close the case so it does not move until you open the case and move the button so it will work.