The Zenith 4001 is a calibre by Zenith.
Further development of the self-winding movement Zenith 410 ( El Primero ) with bi-directional winding ball bearing central rotor (Gold Inertia). With flyback function, day of the week, month and date display and moon phase.
Used e.g. with the model Zenith Grande Chronomaster GT “El Primero”.