A topic that pops up daily across the watch modding world is the line of NH movements and their background.
The first question is always, "are the NH movements the same as Seiko movements?" In a word, no, not really.
Seiko movements are made in Japan and Japan only. To leave the factory they must pass through a rigorous QAQC process. Whether it's their entry level movements (e.g. 4R34, 4R35, etc.) to their midrange movements (e.g. 6R15, 6R54...) to their upper level series (typically has an "L" in place of the "R" in the title, e.g. 8L55), each product is made in a controlled environment and thoroughly inspected. Once complete, they are then shipped out.
The NH movements are made by a subsidiary of Seiko - TMI - or Time Module, Inc. Their movements are made in Indonesia, Malaysia and China, for the most part. The QAQC processes at any one of those factories isn't quite to the standard of the ones in Japan.
Some are churned out of Japan. Once that fact gets thrown out into the conversation, two questions are invariably asked:
"Can you tell the difference between the ones that come out of Japan from the other factories?" No, you can't.
"Do I have the option of choosing an NH movement from Japan instead of the other sites?" No, you can't.
Prior to the tariff wars, NH movements were the way to go if you wanted to build your watch and just have fun learning the processes behind watchmaking and watch repair.
Since the prices more than doubled over the last year, the efficacy of choosing an NH movement over the cost of just buying a Seiko movement is shrinking more and more. Prices on eBay for a 4R35 movement are running around $110 USD, while on AliExpress an NH35 movement averages around $70. Whereas in the Summer of '24, an NH35 movement would cost between $25 and $35 US.
Where the gap really shrank was with the NH34 movement. That movement has gone from $40 to $50 USD to typically around $125 to $140 USD. Why pay that kind of money for an NH34 when you can buy a 4R34 movement for $160?
It's these rising costs that are starting to raise the prices for any and all types of watches.
Below is a quick reference chart of the movements and their counterparts:
NH34 → 4R34 → 6R54
NH35 → 4R35 → 6R15/6R35
NH36 → 4R36
NH38 → 4R38
NH39 → 4R39
All of the movements feature share the same beat rate - 21,600bph, share the same dimensions, same jewel count and both feature the same hacking and hand-winding capabilities.