Citizen Original Spare Part – Mainspring – Size 新中三 (1.45 × 0.110 × 335 mm) – NOS (1 Piece)

Original Citizen spare part – mainspring (Japanese ぜんまい/zenmai) from unused old stock (NOS). Offered is a single mainspring in original Citizen packaging with the historic "CITIZEN MAINSPRINGS" crest.

The mainspring is the energy reservoir of the mechanical movement: coiled in the barrel (香箱), it is wound via the crown and, by unwinding, drives the entire gear train. As a central power source and wear part, it fatigues over time, can take a permanent set, or break – a suitable replacement is essential for every overhaul.

Specification (according to original label):

• Size: 新中三 (Citizen size code)
• Width: 1.45 mm (Dennison strength 4)
• Thickness: 0.110 mm
• Length: 335 mm

For a factory-original, authenticity-oriented restoration, a genuine Citizen mainspring in its original packaging is the first choice – especially for collectors who want to preserve the original condition of their watch.

The part is unused (NOS) and comes from decades of storage. As with any genuine NOS part – comparable to original NOS vintage car spare parts – age is part of its authenticity: a stored carbon steel spring may have taken a slight permanent set, lost some elasticity, or be superficially darkened/slightly corroded. For authenticity-oriented collectors, this is precisely the appeal – a period-correct original part instead of a modern replica. Traces of storage may also be present on the foil and packaging.

Manufacturer: Citizen (Citizen Watch Co., Japan). The style of the packaging and logo roughly dates the piece to the 1950s/60s.

Warranty (used)
This is an original part (NOS) stored for decades. The limitation period for claims for defects (statutory warranty) is 12 months from delivery.

Note
For those who value originality in a vintage watch – a particularly high standard in the Japanese collector's market – this genuine, period-correct Citizen mainspring is the right choice. Before installation, please check the condition and compare the dimensions (width × thickness × length) and the barrel fit with the target caliber; installation should be carried out by a professional.