Snap-On Sapphire Back
Perpetual Calendar 3971 — Snap-On Sapphire Back
Undated
Sold concurrently with the first-series 3970, with a snap-on display back.
Fewer than 300 made.
No verified image of this watch yet
Identifying details
- Perpetual calendar
Calendar that accounts for month lengths and leap years.
- Moon phase
Variants of 3971
Reference overview →| Variant | Production |
|---|---|
| Snap-On Sapphire BackCurrent | Undated |
| Ref. 3971E, Screw-Down Sapphire Back | 1987–1990 |
Case & movement
- Reference
- 3971
- Production
- Undated
- Case diameter
- 36 mm
- Movement
- Manual winding
- Date
- Yes
- Caliber
- Patek Philippe CH 27-70 Q
Dial, bezel & hands
Unknown attributes are left out rather than guessed.
Movement
Patek Philippe CH 27-70 Q
Heavily modified Lemania 2310 column-wheel chronograph with perpetual calendar, moon phase, leap-year and 24-hour indications. Replaced the Valjoux-based in the ref. 3970 and also powered the ref. 5020.