Seiko NH37A

Seiko Instruments (TMI) · Automatic · Entry tier · Family: Seiko NH3x

NH3x-family automatic with a date and a small 24-hour indicator subdial ("Three Hands with 1 Eye & Date, Small 24 Hour Indicator Hand"). The 24-hour hand is synchronised with the regular hour hand (a day/night indicator, not an independently set GMT), so `functions` lists only hours, minutes, seconds and date. TMI spec sheet (version 1, rev. 16.11.2022): 12 lignes, Ø27.40mm (Ø29.36mm with the dial holding spacer), 5.32mm high, 24 jewels, 21,600 vph, duration "more than 41 hours", accuracy -20 to +40 s/day (23 ±2 °C), manual winding, ball-bearing automatic winding in both directions, second hand stop mechanism (hacking), date display with quick date correction, antimagnetic ≥4800 A/m; country of origin "Japan or Malaysia". TMI's casing notes say a screw-type case back is required and that the caliber is "non-corresponding with diver's watch". Siblings: NH35 (date, no 24-hour indicator), NH39 (open heart and 24-hour indicator, no date).

Watches with the Seiko NH37A

Watch	Price from	Movement	Dia. mm	Thick mm	Crystal	Micro-adjust
Aquatico Bronze Pilot	$359	Seiko NH37A	43	12.5	Sapphire	—
Undone Aquadeep (NH37)	$595	Seiko NH37A	43	16.5	—	no bracelet

Sources

• Time Module (TMI), NH37A watch movement specification and drawing (version 1, rev. 16.11.2022)
• Time Module (TMI), Mechanical (NH0 & NH3) product line-up (NH37, 12''', 5.32mm, 3 hands / date, 24 hour)