Cal. 670 SK is an automatic movement with silicon components from Zenith. It is a compact 25.60 mm movement with date used in Elite and Defy models. Unusually for a Zenith Elite movement, it features a central seconds hand. The similar Cal. 670 has traditional components and is somewhat thinner.
It features a silicon pallet lever and escape wheel.
Cal. 670 SK is available in a skeletonized version as well. Cal. 670 SK is listed as containing 187 components rather than 144 on the regular Cal. 670 and is 3.88 mm thick rather than 3.47 mm.
Technical Aspects of the Zenith Elite Movement
The basic Elite movement measures 11.5 ligne (25.60 mm) diameter and most models are under 4 mm thick, despite a central automatic winding rotor and date complication. A few models used a larger main plate to move the date window outward or to support complications like a running 24 hour ring. The thinnest Elite movement is the hand-winding Cal. 650 at 2.83 mm and the thickest and most complicated is the large Cal. 687 at 6.20 mm.
Unusually, many Elite movements (apart from the 660 and 670 lines) feature small seconds at 9:00, a distinctive feature that differentiates the watches that use it. Some, however, feature central seconds, an adjustable 24 hour hand, a power reserve indicator, and other complications.
All Elite movements use an annular Glucydur balance wheel with a self-compensating balance spring and fine micrometer screw for adjustment. The automatic winding rotor is mounted on ball bearings like the ETA 2892 and originally included a tungsten carbide element for higher winding power. Most Elite movements boast 50 to 55 hours power reserve and all operate at 28,800 A/h.
Zenith Elite 670: Central Seconds
Cal. 670 was one of the original Elite movements, and remains in production as of 2020. It has central seconds, unlike most Elite movements, and serves as a base for a few complicated versions. Cal. 670 SK, introduced in 2018, is especially notable, as it includes a silicon escapement and is often skeletonized.
| Movement | Years | Winding | Jewels | Complications |
|---|---|---|---|---|
| Elite 670 | 1994-present | Automatic | 27 | Date |
| Elite 670 SK | 2018-present | Automatic | 27 | Date, Skeleton |
| Elite 672 | 1996-2014 | Automatic | 27 | Date, 24 Hour Hand |
| Elite 679 | 2009-present | Automatic | 27 | None |
| Elite 67 | 2004-2008 | Automatic | 27 | None |