"JDM" means Japanese Domestic Market: a model built for sale inside Japan. "NOS" means New Old Stock: an unworn piece from an earlier production run. Both terms appear often in Seiko Presage listings, and both affect what you are buying. Here is what they mean in practice for a UK buyer, and which references are worth holding.
JDM versus international models
Seiko sells different model lines in Japan and abroad. JDM references often carry Japanese text on the dial or caseback, slightly different finishing, and reference codes ending in "J". The movement and quality are the same standard Seiko applies globally; the distinction is market and presentation, not a lower or higher grade. For collectors, a JDM piece offers a subtle point of difference from the international version.
The 4R35 movement
Most Presage Cocktail Time references use Seiko's 4R35 automatic. It runs at 21,600 beats per hour, holds roughly a 41-hour power reserve, and supports both hand-winding and hacking seconds. Its official accuracy is rated at minus-15 to plus-25 seconds per day, though well-settled examples commonly run inside plus-10 to plus-20. It is a dependable, serviceable movement that has earned its reputation across millions of watches.
The box Hardlex crystal
Cocktail Time models use a box-shaped Hardlex crystal, Seiko's domed mineral glass. It is not sapphire, and that is a deliberate choice at the price: the domed profile catches light across the dial and adds the depth the range is known for. It is more prone to scratches than sapphire but simple and inexpensive to replace.
References worth owning
The dial is where these watches earn their following. We currently hold several, including the espresso-black SRPE17J1, the ice-blue 'Skydiving' SSK037J1, the navy 'Blue Moon' SRPB41J1, and a rare NOS 'Red Garnet' JDM edition.
Buying in the UK
When you buy a JDM Seiko already stocked in the UK, the import duty and VAT have been handled before it reaches you, so there are no surprise charges on delivery. That is the practical advantage of buying a JDM piece domestically rather than importing it yourself.
Why it is worth owning
A Presage offers genuine mechanical watchmaking and one of the most admired dials at its price. Every piece we list is inspected, photographed as the watch you receive, and shipped from the UK, fully tracked and insured. Explore the full range in our Seiko collection.