ETA SA F385

Cal. F385 is an automatic chronograph movement manufactured by ETA SA. It measures 37 mm in diameter and 5.0 mm thick, operating at a high frequency of 5 Hz (36,000 A/h) with a free-sprung Glucydur balance and silicon balance spring. The chronograph mechanism uses a column wheel and vertical clutch to enable the flyback function. The movement remains in production and powers models such as the Blancpain Bathyscaphe Chronographe Flyback.