The International Durowe 450 is a open face calibre watch movement that features a Breguet hairspring. It also offers the option of a Reed's regulator. The specific differences between the Felsa 160, 162, and 165 are unknown. It is worth noting that while the movement registers list only the open-face variant of the Felsa 161, Ronda additionally mentions the Felsa 160, 162, and 165. The functions of the International Durowe 450 include stem wind and set, as well as sub second. This movement was commonly used around the period of 1932.