The NH36 has been one of the most popular choices for watch movements used in Seiko modding. In fact, it is most often used with the SKX007 one of if not the most popular reference watches in watch modification. This perfectly matching parts can both be bought here.

If you are new to modding and want to know more about the NH36, you are in the right place. The movement is the most important part of a watch for without it, you will only have a useless piece of metal on your wrist.

Quick Trivia: Another term for a watch movement is the calibre, or clockwork.

Seiko has been known to make high quality watch calibers for over a hundred years now, and they are still innovating up to this day. What's more, they have been making affordable movements especially when compared to their Swiss counterparts. Just a few decades after they popularized the Quartz movement and almost extinguished the Swiss watchmaking industry, Seiko came up with the 7S series of watch movements which include the 7S26, 4R36 and 6R15.

This series powers the most recognizable diver watches today including the SKX007, SKX013, and the SRP777 Turtle. The main features include:

  • Holding a 40-hour power reserve
  • 21 jewels arrangement for better functionality
  • Accuracy of -20 to +49 seconds

While the initial accuracy of the 7S movements were not something to brag about in this day and age, it is a feat back in its day and have been constantly evolved into more precise mechanisms. When the original SKX007 came out in 1996 carrying the much improved 7S26, it became a runaway success and cemented the status of the movement as being one of the most popular in history.

Years later still, Seiko, via its subsidiary the Seiko Instruments Inc. (SII) made more improvements to the infamous caliber by adding hacking and hand-winding features. This resulted in the Seiko-branded 4R series. Later on, they would create unbranded versions of these movements which were released as the NH35 and NH36.


These two NH movements were made for microbrand watches like the Undone Aero or the Dan Henry, but more importantly, they have become the movement of choice for Seiko modders. These are very affordable and easily accessible, and it is a perfect fit for SKX-style cases which are the most commonly modded watches to date. What's more, these can be regulated to have extremely precise timekeeping an important feature for any watch enthusiast.

As mentioned before, the NH series includes the NH35 and the NH36 which you can both get from our shop. The latter comes with a day and date complication while the former comes with date only. Make sure to get the correct one for the dial you are using!

Just something to note, the NH36 movement is intended for 3 o'clock watches. While you can use it with a 4 o'clock case like the SKX007's, the date wheel will be misaligned so you will have to source one from a 4 o'clock movement, the most common being the 7S26 (the OEM movement on most SKX watches).

We hope this gives you a bit more info! You can check out this blog post if you want to know more about watch movements (trust me, they are fascinating).

For other inquiries or concerns, please feel free to reach out to us at

Happy modding!

August 19, 2021 — Jeremiah A