The Seiko 4205B watch movement features a rotor that is positioned out of center. The winding gear is integrated into the movement, resulting in a remarkably thin movement for its time. It also incorporates a detached manual wind feature and an escapement from Helvetia. The inclusion of Kif-Duofix combined settings for the escape wheel enhances its durability. Additionally, this movement offers automatic winding, sweep second function, Incabloc Shock Protection, and was commonly used around 1965.