Certina 13.20-404, Winding stem, inner, female

• CERTINA original inner winding stem without factory packaging.
  

• Fits cal: 13-20, 13-21, 13-22

Versions:

• 13-20: N: = 19.800, no mountings.
• 13-21: N: = 19.800, mounting threads.
• 13-22: N: = 21.600, mounting threads.