The Zenith 133.8 watch movement was introduced during the period of 1975-1977. It is similar to the 25-651 model, but it features a balance with three spokes instead of two and a larger plate recess for the lever cock. Additionally, there is a choice between a bevelled and plane date disc. During the transition period, old and new components were arbitrarily mixed, resulting in incorrect signatures. The movement encompasses automatic winding, a sweep second hand, and a date function that can be adjusted by changing the time from 23-24h.