Certina 15.20-404, Winding stem, inner, female

• CERTINA original inner winding stem, not in factory packaging.

• Fits cal: 15.20, 15.21, 17.211, 17.221

Versions:

• 15.20: 6.75''' 19.800 A/h.
• 15.21: 6.75''' 21.600 A/h.
• 17.211: 7.75''' 21.600 A/h, date.
• 17.221: 7.75''' 21.600 A/h, date, modified balance.