Calibre 863 — the 861 dressed for a display back

In brief

The chronograph brake is metal here, not the plastic Delrin part Omega used in the 861, and the decoration has been lifted a grade. Under that, the same cam-switched mechanism running at 21,600 vph — built for Speedmasters with a transparent caseback.

Short history

Like the 861, it works from the Lemania 1873 ébauche. From 1985 Omega used it in the first Speedmaster references with a glass caseback, the 345.0808 among them (1985–1988) — watches designed so the movement could be looked at, finished to a standard the ordinary 861 never received.

Watches that used it

• Speedmaster ref. 345.0808 (display caseback)