Patek Philippe used a F. Piguet ebauche to produce their own ultra-thin 9 ligne watch movement. Although based on this venerable design, Patek Philippe modified the movement extensively. They added their patented free-sprung Gyromax balance and finished the movement to Geneva Seal standards.
Cal. 175 beats at a leisurely 18,000 A/h, but the derivative Cal. 177 beats at a more modern 21,600 A/h. Apart from this, the movements are very similar.
Cal. 177 remains in production.
Cal. 175 and 177 was used in many watches, including the following popular references:
- Piguet 21, the ebauche