What’s the difference between SII or TMI movement

The many different names of Seiko movements 

Short answer: the only difference is the name. 

Shopping for a Seiko movement nowadays can be a confusing process, simply because of the multitude of different names it can take on. You might see a SII or TMI movement instead of a Seiko movement. Does that imply a certain difference in the movement you’re purchasing? In this short guide, we will unravel the reason behind these different names and why they essentially mean the same thing.

What are SII and TMI

Seiko as a company is a conglomerate, meaning that it is a collection of subsidiaries controlled by Seiko Holding Group. SII and TMI are simply subsidiaries of the Seiko Group.

SII, or better known as Seiko Instrument Inc., is based in Chiba Japan. Seiko Instruments became a wholly-owned subsidiary of Seiko Holdings on October 1, 2009, through a business merger.

TMI, on the other hand, is a trademark previously owned by a company in Hong Kong, the Time Module (H.K.) Ltd. It was established in 1987 “with original funds from Seiko Corporation, Seiko Instruments Inc. and Seiko Epson Corporation”. Since 2015, it is wholly owned by Seiko Holdings Group. Time Module (H.K.) Ltd has been replaced by SEIKO Manufacturing (H.K.) but they have retained the brand name TMI.

They are the same thing

That means SII and TMI are both trademarks owned by the Seiko Group. That’s why you’ll see their name as equivalent to the Seiko name on many movements. Because they really are. The name difference shows simply how their business is structured. Distribution, reseller, marketing, etc. The underlying movement that you get is still the same Seiko movement.

So in short, SII = TMI = Seiko. That’s it. They are just different names for the same thing.