The ChronoMaster Open Grande Date is an extension of the ChronoMaster Open, but with a new complication and black or silver sun guilloche dial with hand-mounted appliqué indexes and numerals. Inside Information: The Zenith El Primero was the first high-frequency, and therefore high-performance, chronograph movement when it was designed in the 1960s. The ChronoMaster Open is perhaps Zenith’s most attractive design that offers a taste of the historic engine inside.
