• Manufacturer: Seiko (SII, TMI)
• Caliber Number: NH35A (also known as NH35)
• Movement Type: Automatic, self-winding mechanical
• Lignes: 12”’
• Diameter: 27.40mm
• Casing Diameter: 29.36mm
• Height: 5.32mm
• Jewels: 24
• Vibrations Per Hour: 21,600 bph
• Lift Angle: 53 degrees
• Shock System: Diashock
• Power Reserve: 41 hours
• Rotor Direction: Bi-directional winding (Magic Lever)
• Functions:
• Central hours
• Central minutes
• Central sweeping seconds
• Date calendar at 3:00 (position may vary based on dial design)
• Hand-Windable: Yes
• Manual Winding: Clockwise direction
• Hand Sizes: 1.5mm / .89mm / .21mm
• Stem: 351-200 / 351200 (tap 10)
• Hacking Seconds: Yes
• Country of Manufacture: Japan or Malaysia

The NH35A is recognized as a hand-windable and hacking upgrade from the Seiko caliber NH25A. It gained prominence around 2011-2012, coinciding with its initial use in watches hitting the market. This movement has gained widespread popularity and is commonly found in numerous affordable and microbrand watches.

NH35A Insights:

The NH35A shares similarities with the Seiko caliber 4R35, being essentially an unbranded version. It showcases an accuracy range of approximately -20 to +40 seconds per day, as documented by Time Module Inc. Accuracy tests should be conducted within 10-60 minutes after a full winding to ensure reliable results.

Winding and Crown Functions:

Fully winding the NH35A requires about 55 manual turns of the crown. Equipped with the Seiko Magic Lever, gently shaking the watch sideways initiates the movement almost immediately. The crown positions offer different functions for manual winding, date setting, and time adjustment.

Variations and References:

The NH35A presents various reference numbers based on production variables, including the movement's origin, date position, calendar color, and hand fitting type. Date positions at 3:00 or 6:00, different date disc colors, country codes denoting production origin (J for Japan, M for Malaysia), and hand fitting types (M or L) contribute to the movement's variations.

Rotor Variations:

Despite the preference for custom rotors by many watch brands using the NH35A, official tech sheets from March 2017 indicate the availability of two stock rotors based on the movement's origin: Japan or Malaysia.

• Manufacturer: Seiko Instruments (SII), Time Module (TMI)
• Caliber Number: NH34, NH34A
• Movement Type: Automatic
• Lignes: 12”’
• Diameter: 27.4mm (29.36mm with spacer)
• Height: 5.32mm thick
• Jewels: 24
• Vibrations Per Hour: 21,600 bph
• Lift Angle: 53 degrees (needs confirmation)
• Power Reserve: Approximately 41 hours
• Hand Windable: Yes
• Hand Winding Direction: Clockwise
• Rotor Direction: Bi-directional (Magic Lever)
• Anti-Shock System: Seiko Diashock
• Regulator System: ETACHRON
• Hand Count: 4
• Functions: Central hours, central minutes, central sweeping seconds, central GMT hand, date at 3:00
• Hacking Seconds: Yes
• Country of Manufacture: Japan or Malaysia

The NH34A is an automatic movement based on Seiko branded 4R34 and is a member of the NH family of movements, distinguished by the GMT complication (24-hour hand). Released in Summer 2022, this movement enhances the NH35 by adding the additional 24-hour hand.

Differences between NH34, NH34A, and NH34B:

NH34 represents the base caliber number, and the letter signifies any updates or iterations to the movement. NH34A is the initial generation, indicating the first version of this caliber. Presently, only NH34A is available.

Accuracy and Power Reserve:

Time Module claims NH34's factory-adjusted accuracy to range between +40/-20 seconds per day, based on normal daily wear between temperatures of 2 ºC and 23 ºC. When testing timekeeping accuracy, ensure the watch is fully wound. Seiko notes that actual daily rates may vary due to usage conditions like wrist-wearing duration, temperature, arm movement, and the mainspring's winding status.

The NH34-powered watch, when fully wound, offers a power reserve of approximately 41 hours. Winding the watch in a clockwise direction is recommended, and the movement cannot be overwound.

NH34 Crown Position Functions:

- Position 0 (against the case): Clockwise = Manual Winding / Counterclockwise = No function

- Position 1 (pulled out one click): Clockwise = Adjust GMT hand / Counterclockwise = Date setting

- Position 2 (pulled out two clicks): Clockwise and counterclockwise = Time setting

These details outline the unique characteristics and functions of the NH34A movement, enhancing its performance and usability within watch mechanisms.

Specifications of the VK63:

• Manufacturer: Hattori, also known as Seiko Instruments Inc. (SII)
• Caliber Numbers: VK63, VK63A
• Movement Type: Quartz (mechaquartz)
• Lignes: 13 1/2”’
• Diameter: 30.80mm x 29.10mm
• Casing Diameter: 29.10mm
• Height: 5.10mm
• Jewels: 0
• Battery Cell Number: 394
• Frequency: 32,768 Hz
• Quartz Type: Tuning fork type quartz crystal
• Driver: 2 pole stepping motor
• Stem: 351177 / tap 10 or 351892 / tap 11
• Hand Sizes: 1.50mm / .90mm / .32mm
• Functions: Hours, minutes, small seconds, date, central chronograph seconds, 60-minute counter, 24-hour indicator
• Country of Manufacture: Japan

The SII (Seiko Instruments) caliber VK63 belongs to the category of hybrid mechanical quartz (mechaquartz) movements. This chronograph movement integrates quartz technology for fundamental watch functions while utilizing a mechanical module to operate the chronograph. Sometimes referenced as VK67 and VK83, they share the same base movement as VK63.

Comparison: SEIKO 6T63 VS VK63:

The SII caliber VK63 shares similarities with the Seiko 6T63. The primary distinction lies in their usage, where the VK63 is designed for non-Seiko watch brands under Seiko Instruments, while the 6T63 is specifically used in Seiko-branded watches like the SSB025.

VK63 and Its Variants:

The base caliber number is VK63, with VK63A being the initial version. Subsequent letters indicate advancements in the movement's development. Presently, VK63A is the existing version, but potential upgrades may lead to VK63B, VK63C, and so forth.

Accuracy and Battery Life:

Time Module/Seiko mentions an expected accuracy of less than +/- 20 seconds per month at normal temperatures for the VK63 movement. The estimated battery life is approximately 3 years under regular conditions. Using the chronograph function extensively may reduce the battery lifespan. Changing the battery requires a cell number 394 (SR936SW) and resetting the circuit for proper functionality.

The Seiko NH38A caliber, is an automatic, self-winding mechanical movement notable for its specific characteristics:

• Caliber Number: NH38A
• Movement Type: Automatic, self-winding mechanical
• Diameter: 27.40mm (outside) / 29.36mm (casing)
• Height: 5.32mm
• Jewels: 24
• Vibrations Per Hour: 21,600 bph
• Anti-Shock System: Yes
• Power Reserve: 41 hours
• Rotor Winding Direction: Bi-directional (Seiko Magic Lever)
• Functions: Central hours; central minutes; central sweeping seconds
• Hacking Seconds: Yes
• Notable Features: No-Date, open balance wheel
• Country of Manufacture: Japan/Malaysia

This caliber, the NH38A, exhibits a no-date design with an open balance wheel, demonstrating Seiko's craftsmanship and engineering expertise. Crafted in either Japan or Malaysia, this movement offers reliable performance with its self-winding mechanism and notable accuracy, representing a hallmark of Seiko's watchmaking excellence.

Distinguishing NH38A from NH35A:

Unlike its counterpart, the NH38A is a simplified three-hand watch without any day or date complication. Additionally, it boasts partial skeletonization, showcasing an exposed balance wheel within its design.

Accuracy Rating:

According to Time Module (TMI), the NH38A maintains an accuracy rating of -20 to +40 seconds per day, meeting the declared performance standards.

Origin:

The complete Japanese-made caliber number is NH38A3J, while its Malaysian equivalent is officially designated as NH38A3M. However, these extended numbers primarily serve as reference codes for ordering purposes and are typically not engraved on the movement itself. The majority of movements do not bear a country of origin marking, leaving the production origin somewhat ambiguous.

• Manufacturer: Seiko (aka Seiko Instruments, SII)
• Caliber Number: NH72 (aka NH72A)
• Movement Type: Automatic
• Lignes: 12”’
• Diameter: 27.4mm
• Casing Diameter: 27mm
• Height: 5.32mm thick
• Jewels: 24
• Vibrations Per Hour: 21,600 bph (3Hz) (6 beats per second)
• Lift Angle: 53 degrees
• Shock System: Diashock
• Power Reserve: ~41 hours
• Winding Direction: Bi-directional (Magic Lever)
• Hacking: Yes
• Hand-Windable: Yes
• Hand Count: 3
• Functions: Central hours, central minutes, central seconds
• Country of Manufacture: Japan/Malaysia

The Seiko caliber NH72, also known as NH72A, is an automatic movement renowned for its skeletonized design and lack of date feature. This three-handed caliber belongs to the NH family of movements, specifically the NH7X series characterized by skeleton dials, including the NH70 and NH71 models.

NH72 vs. NH70 / NH71:

The NH72 differs from its predecessors NH70 and NH71 primarily due to its unique Ruthenium Grey color, a lightened PVD coating covering the entire movement, including the rotor. This distinctive hue, introduced in June 2022, distinguishes the NH72 and might signify Seiko's response to customizations seen in the NH7 series.

Accuracy and Functions:

Time Module specifies an accuracy range of -20~+40 seconds per day for the NH72A under normal conditions. Similar to other NH movements, the NH72A is hackable and hand-windable, boasting three crown positions. It features hacking functionality, halting the second hand in time setting mode. The movement should be fully wound after approximately 55 manual turns of the crown, benefiting from the Seiko Magic Lever for prompt initiation.

Country of Origin:

Manufactured in Japan or Malaysia, the NH72 movements often bear country-of-origin markings on the rotor. However, some movements lack these markings, especially those distributed by China-based factories, leading to uncertainties regarding their origin. Seiko's documentation doesn't mention China as a production origin, but some vendors suggest Chinese production, creating inconsistencies in the information available.

The NH72A movement's accuracy, hacking capability, and distinctive Ruthenium Grey color showcase its excellence and unique attributes within the NH series of Seiko movements.