Swiss Made 1600-1803 Mainspring Strength-Standard for Rolex Manual Winding Movement. Mainspring #770/131
For Caliber Numbers: ROLEX 1600, ROLEX 1601, ROLEX 1602, and many more.
***Time Connection II Inc. is independent of and not affiliated with or sponsored by Rolex Watch U.S.A. Inc. Rolex warranty does not apply to non-genuine parts supplied by Time Connection II Inc.***

