Seiko Caliber 4R72

Manufacturer	Seiko
Caliber Number	4R72, 4R72A
In-House?	Yes
Movement Type	Automatic, self-winding mechanical, skeletonized
Diameter	27.4mm
Casing Diameter	27mm
Thickness	5.32mm
Jewels	24
Beat Rate / Frequency	21,600 bph / 3 Hz
Lift Angle	53 degrees
Accuracy Rating	-35~+45 seconds/day
Power Reserve	~41 hours
Rotor Type	Ball-bearing system, 1 screw
Hand Windable?	Yes
Hand-Winding Direction	Clockwise
Rotor Winding Direction	Bi-Directional (Magic Lever)
Anti-Shock System	Seiko Diashock
Regulator System	ETACHRON
Functions	Central hours; central minutes; central sweeping seconds
Hacking Seconds?	Yes
Country of Manufacture	Made in Japan
Known Models	Seiko Presage Cocktail Time STAR BAR (Ref: SSA455, SSA457) (Add your watch in the comments below…)

The Seiko caliber 4R72 (4R72A) is a skeletonized gold-plated (gilt) automatic used by Seiko Watch Corp. in their own branded watches.

This movement is found in the Seiko Presage Cocktail Time STAR BAR Limited Edition watches that were introduced in 2022.

Caliber 4R72 VS 4R71:

There is also a similar caliber 4R71. The difference between the two is color: The 4R72 is gold tone, where as the 4R71 is silver tone. Everything else is the same, including dimensions, jewels, accuracy, etc.

Caliber 4R72 VS SII NH71:

The caliber 4R72 is basically a Seiko-only version of the NH71. Unintuitively, the NH72 is black; the NH71 is gold (gilt).

Seiko Instruments (aka SII) sells NHXX movements to other watch brands for use in non-Seiko watches.

Differences Between 4R72 and 4R72A?

The A indicates that it is the first generation of this caliber. 4R72 and 4R72A are the same, until Seiko releases a 4R72B which will be a second generation (if ever).

Accuracy Rating:

Seiko claims that the accuracy of caliber 4R72 is between +45 / -35 seconds per day. This rating is based on normal daily wear on the wrist in temperatures between 5º C and 35º C. When testing your watch for timekeeping, make sure it is fully wound.

Crown Position Functions:

• 0 (against the case): Clockwise = Manual Winding / Counterclockwise = Nothing
• 1 (pulled out one click): Clockwise = Day setting / Counterclockwise = Date setting
• 2 (pulled out two clicks): Time setting clockwise and counterclockwise

Stem Removal:

To remove the stem, make sure the crown is in position 0 or normal position (not date or time setting position). There is a lever with a small indentation for your tool. Gently press down while pulling the stem out. See official instructions below for more guidance:

Examples of Watches With This Movement:

Additional Resources:

• Official 4R72 user manual (pdf)