Zenith 40-440, Spring for yoke

• ZENITH original part in very good used condition.
  

• Fits cal: 40, 40T
  

Data: Zenith cal: 40

• 17 jewels, manual wind, sub second.
• Size: 12''' 26.75 mm.
• H: = 3.80 mm.
• N: = 18.000 A/h.
• Power reserve: 45 h.
• Mainspring: 1.55 X 10.5 - 0.105 - 380

Versions:

• 40:   1955 - 1960, "screw" balance.
  
• 40T: 1958 - 1963,  flat balance ring.