A Seiko GMT movement - the workhorse for an automatic GMT watch.

A reliable movement from with date function and a 2nd hour function (also known as GMT function). NH34 is currently the most affordable GMT automatic movement, and a near identical version is powering the Seiko Sports 5 GMT.

Key specifications:

Caliber number: Seiko NH34A (aka NH34 or 4R34)
Up to 41 hours of power reserve
Movement type: automatic
Frequency/Vibrations per hour: 21600 bph
Accuracy: -20~ 40 sec per day
Hack-second or stop-second feature allows you to set the time precisely
24 Jewels
Function: 4 Hands including a 2nd hour hand for GMT function, automatic and manual winding, date function
Winding Direction: Clockwise
Diameter: 27.40 mm

Application and SEIKO MOD COMPATIBILITY:

NH34A and NH35A share the same outer dimensions. Therefore NH34A can replace existing NH35A movements as a GMT upgrade to the watch, you will need a GMT compatible dial & an NH34 compatible GMT watch hand, or you'll most probably need two small modifications to the watch assembly process. Please refer to for more details.