ETA SA M100

The M100 is an automatic movement manufactured by ETA SA, introduced in 2016 as part of the A10 caliber family. It measures 42mm in diameter, beats at 28,800 vph, and has a 25-jewel count with a central winding rotor. The movement features an "open heart" design with the balance wheel visible at 6:00 and includes hacking seconds. It remains in production and is also used by Perrelet as caliber P-391.