Japan Genuine NH38 Automatic Movement Open Heart 24 Jewels High Accuracy

The Seiko NH38 Automatic Movement is a pure no-date automatic movement, designed for enthusiasts who appreciate dial symmetry and mechanical transparency. This 24-jewel caliber powers hours, minutes, and sweeping seconds with reliable precision. Featuring hand-winding and hacking capabilities, it operates at 21,600 vibrations per hour. Ideal for skeleton, open-heart, or minimalist builds, its clean dial-side architecture eliminates the "ghost" crown position found in date movements, offering uncluttered aesthetics and simplified operation .

Detailed Specifications:

• Movement Brand: Seiko Instruments Inc. (SII) / Time Module Inc. (TMI)

• Caliber Number: NH38A

• Type: Automatic, Mechanical

• Functions: Hours, Minutes, Sweeping Seconds (No Date/No Day)

• Jewels: 24

• Frequency: 21,600 A/h (3 Hz / 6 beats per second)

• Power Reserve: Approx. 41 Hours 

• Winding: Automatic (Bi-directional "Magic Lever"), with Manual winding capability

• Hacking: Yes (Seconds hand stops for precise time-setting) 

• Accuracy Rating: -20 ~ +40 seconds per day (23º± 2ºC) 

• Regulation System: Triflat (standard regulator)

• Crown Positions: Position 0: Hand-winding; Position 1: Time-setting (hacking) 

• Diameter: 27.4 mm (12 1/2 lignes) 

• Height: 5.32 mm 

• Shock Protection: Seiko Diashock system