The ETA 2658 watch movement, used from 1969 to 1972, features an automatic mechanism with a ball-bearing rotor for efficient winding. It also incorporates a ball-bearing crown wheel for smooth operation. The movement is equipped with an excenter regulator to ensure accuracy. Additionally, it includes a sweep second hand and a date function that can be set by changing the 19-24-hour indication. It is worth noting that there is no discernible difference between the 138 and 2552PC variations of this movement.