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The Encyclopedia of Horology

Movement record · Germany (Glashütte)

A. Lange & Söhne calibre L921.4

Partially verified

A three-quarter plate movement in German silver with gold chatons, blued screws and hand-engraved balance cock, laid out so that the asymmetric Lange 1 dial has each indication over its own mechanism.

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Technical specifications

Diameter
Not recorded in a source consulted here
Height
Not recorded in a source consulted here
Jewels
45 jewels (per cited source)
Frequency
21,600 vibrations per hour
Power reserve
Approximately 45 hours
Winding
Manual winding
Setting
Crown setting, with the outsize date advanced by a pusher
Escapement
Swiss lever
Balance
Screwed balance with swan-neck fine adjustment
Complications
Outsize date, Power-reserve indication on the Lange 1 family

Identification features

  • Three-quarter German silver plate with hand-engraved balance cock
  • Twin barrels on some variants of the family
  • The movement includes a zero-reset mechanism that stops the seconds hand at zero.
  • It features a 21-karat gold central rotor integrated with a three-quarter plate architecture.

Known variants

  • Several numbered variants within the L901 / L921 family

Servicing notes

Factory service only; components are not available to the independent trade.

General guidance only. Antique movements should be serviced by a qualified watchmaker.

Historical significance

The calibre family with which Lange re-established Glashütte watchmaking after German reunification.

Introduced in 1997, the calibre L921 was A. Lange & Söhne's first automatic movement, known as the Sax-O-Mat. The name reflects its Saxon origins, automatic mechanism, and the zero-reset function that returns the seconds hand to zero upon pulling the crown. Designed by Helmut Geyer, this movement utilizes a 21-karat gold central rotor to maintain the architecture of the three-quarter plate.

The added history summarises the open references listed under Sources; each statement was checked against the cited passage.

Photographs

A. Lange & Söhne caliber L921.4 » WatchBase
A. Lange & Söhne caliber L921.4 » WatchBase — watchbase.com, Rights unverified — web image search result, review pending. Web page (watchbase.com)
A Symphony of 72 Masterpieces: 30 Years of Calibre Development at A. Lange & Söhne - Swisswatches Magazine
A Symphony of 72 Masterpieces: 30 Years of Calibre Development at A. Lange & Söhne - Swisswatches Magazine — swisswatches-magazine.com, Rights unverified — web image search result, review pending. Web page (swisswatches-magazine.com)
The Collector's Guide and Review of A. Lange & Söhne Langematik
The Collector's Guide and Review of A. Lange & Söhne Langematik — langepedia.com, Rights unverified — web image search result, review pending. Web page (langepedia.com)

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. A. Lange & Söhne Saxonia 315.026 White gold Silver Hungary, everywatch.com, retrieved 2026-11-04 (paraphrased; text © the publisher)
  2. A. Lange & Söhne caliber L921.4, dials.co, retrieved 2026-11-04 (paraphrased; text © the publisher)
  3. Reference 308.025 Sax-O-Mat | A platinum automatic wristwatch with date and zero reset function, Circa 1998 | Important Watches | 2024 | Sotheby's, sothebys.com, retrieved 2026-11-04 (paraphrased; text © the publisher)
  4. A. Lange & Söhne automatic calibres: from Sax-O-Mat to Datomatic | Tatler Asia, tatlerasia.com, retrieved 2026-11-04 (paraphrased; text © the publisher)
  5. Manufacturer descriptions of the Lange 1 calibre family
  6. Variant numbering within the family is reported inconsistently outside factory documentation.

Where sources disagree, the disagreement is stated rather than resolved silently.