Versions:
- 27B: sub second. (1950 - 1961).
- 27B.1: sub second, incabloc. (1950 - 1961).
- 27B.2: sweep second. (1950 - 1961).
- 27B.21: sweep second, incabloc. (1950 - 1961).
- 27B.61: sweep second, date hand, incabloc. (1950 - 1961).
- 27B.621: sweep second, date, incabloc. (1950 - 1961).
- 27B.9: no second, incabloc. (1950 - 1961).
