|Brand:||Seiko, Seiko Instruments Inc., Time Module Inc.|
|Winding:||Automatic, Bi-Directional Automatic Winding|
|Diameter:||27.40 mm (12 ligne)|
|Complications:||Hacking Seconds, Hand Winding|
|Hands:||Central Hour Hand, Central Minute Hand, Central Seconds Hand, Open Heart at 9:00|
|Production: 2018 – Current|
Seiko Cal. 4R71A (commonly called just Cal. 4R71) is a partially-skeletonized and open heart mainstream automatic movement. It is also offered by Time Module Inc. (TMI) as Cal. NH70A and NH71A (gold plated) for use by other watch makers. It is closely related to the date-only Cal. 4R35 and 4R38.
First appearing in late 2017 for the 2018 BaselWorld releases, Cal. 4R71 has only been used in two limited-edition Seiko Premier watches.
Hand winding is accomplished with the crown in first position, rotating clockwise.
|Spron 510 Mainspring|
NH71A (skeleton, gilt)
|Day and Date||4R36A|
|Date, 24 Hour Subdial||4R37A|
|24 Hour Subdial||4R39A|
|Date by Pointer|