Cal. C99001 is a clone of the Valjoux 7750 produced by Concepto Watch Factory of La Chaux-de-Fonds. It was designed to be 100% compatible with that famous automatic chronograph, exactly the same size and design. One major differentiator was the use of Concepto’s in-house assortiment, including the balance, spring, and anchor.
Cal. C99001 was available in date (C99001-D), day-date (C99001-DD) or plain versions. The similar Cal. C99002 adds a central date pointer and relocates the day and month to the 12:00 subdial.
The following watches are known to use Cal. C99001:
- Sinn 103 St
- Sinn 103 St Sa
- Sinn 103 Ti Ar
- Sinn 144 St Sa
- Sinn 206 Arktis II
- Sinn 206 St Ar