Seiko has added two new colours to its 5 Sports GMT Field Series, and honestly, choosing between them might be the hardest part.
The HDB001K gets a dark green dial that leans into the traditional field-watch look. The HDB002K goes with ivory, giving it a lighter and, in my opinion, slightly more distinctive feel.
Mechanically, they're basically the same watch. So this one really comes down to colour.
Quick Take
- 39.4mm stainless-steel case
- Seiko 4R34 automatic GMT movement
- Around 41 hours of power reserve
- 100 metres of water resistance
- Curved Hardlex crystal
- LumiBrite on the hands and hour markers
- Date display
- Stainless-steel bracelet
- Green HDB001K or ivory HDB002K
What Makes the Seiko 5 GMT Field Series Different?
The big feature is the GMT function.
An extra hand works with the 24-hour scale to track a second time zone alongside your normal local time. It's simple, useful and adds another layer of practicality to the field-watch design.
Both watches use Seiko's 4R34 automatic movement, which can also be hand wound and offers around 41 hours of power reserve.
You can also see the movement through the exhibition case back, which is always a nice addition on an automatic watch.
Green or Ivory?
This is where the two watches really separate for me.
The green HDB001K feels like the more traditional choice. It fits the military-inspired field-watch styling naturally, and the darker green gives it that classic, purposeful look you’d expect from this kind of watch.
But the ivory HDB002K is the one I’d choose.
There’s something about the lighter dial against the stainless-steel case and bracelet that grabs me more. It feels cleaner, a little less expected and, to my eye, gives the watch more personality.
I also like that ivory isn’t the colour I’d immediately expect on a field-style GMT. The green looks right, but the ivory makes me stop and look twice.
And when both watches share the same movement, case and functionality, that emotional pull matters.
For me, the green is the classic option. The ivory is the one I’d actually want on my wrist.
Case & Wearability
Both models use a 39.4mm stainless-steel case, measuring 47.9mm long and 13.6mm thick.
I think staying under 40mm is a smart move here. It keeps the watch from feeling oversized on paper, even with the added GMT functionality.
The watch weighs 147g on its stainless-steel bracelet and has a 20mm lug width.
You also get 100 metres of water resistance, which fits nicely with the practical nature of the Seiko 5 Field Series.
Dial & Everyday Features
Both models have a date display, curved Hardlex crystal and LumiBrite, Seiko's luminous material, on the hands and hour markers.
Nothing here feels overly complicated.
You've got an easy-to-understand analogue layout, the added GMT hand and enough practical features to make it more useful than a basic three-hand automatic.
That's probably the appeal.
HDB001K vs HDB002K
Specification | HDB001K | HDB002K |
Dial | Green | Ivory |
Movement | 4R34 automatic GMT | 4R34 automatic GMT |
Case | 39.4mm stainless steel | 39.4mm stainless steel |
Thickness | 13.6mm | 13.6mm |
Power reserve | Around 41 hours | Around 41 hours |
Crystal | Curved Hardlex | Curved Hardlex |
Water resistance | 100m | 100m |
Bracelet | Stainless steel | Stainless steel |
Weight | 147g | 147g |
Final Verdict
The Seiko 5 GMT Field Series is pretty easy to understand.
You get a 39.4mm steel case, automatic GMT movement, around 41 hours of power reserve, 100 metres of water resistance and a stainless-steel bracelet.
So which one would I choose?
Personally, the HDB002K in ivory.
The green HDB001K fits the field-watch theme perfectly, but I think the lighter ivory dial gives the design a bit more character.
That said, there really isn't a wrong choice here. Mechanically, you're getting the same watch.
It just comes down to whether you're team green or team ivory.
Seiko 5 Sports Field GMT HDB001K Automatic
$695.00
The Seiko 5 Sports Field GMT HDB001K Automatic combines rugged field watch styling with the practicality of a dual time display. Its olive green dial features easy-to-read Arabic numerals, a bold GMT hand for tracking a second time zone, and… read more
Seiko Sports 5 Field GMT HDB002K Automatic
$555.00
$695.00
The Seiko 5 Sports Field GMT HDB002K Automatic blends classic field watch styling with modern GMT functionality. Its clean ivory dial features bold Arabic numerals, a striking GMT hand for tracking a second time zone, and a practical date window… read more
Frequently Asked Questions
Q. What is the difference between the Seiko HDB001K and HDB002K?
A. The main difference between the Seiko HDB001K and HDB002K is the dial colour. The HDB001K features a dark green dial, while the HDB002K has an ivory dial. Both Seiko 5 GMT Field Series watches share the same movement, case size and key features.
Q. Is the Seiko 5 GMT Field Series automatic?
A. Yes. The Seiko 5 GMT Field Series uses Seiko's 4R34 automatic GMT movement, which can also be hand wound. It offers approximately 41 hours of power reserve when fully wound.
Q. What does GMT mean on a Seiko watch?
A. GMT allows the watch to display a second time zone. On the Seiko 5 GMT Field Series, the additional GMT hand works with the 24-hour scale, making it useful for travelling or keeping track of another time zone.
Q. How big is the Seiko 5 GMT Field Series?
A. Both the Seiko HDB001K and HDB002K have a 39.4mm stainless-steel case, measuring 47.9mm from lug to lug and 13.6mm thick. They also feature a 20mm lug width and weigh approximately 147g.
Q. Is the Seiko 5 GMT Field Series water resistant?
A. Yes. Both Seiko 5 GMT Field Series models offer 100 metres of water resistance, adding to their practicality as everyday watches.
Q. How long is the Seiko 5 GMT power reserve?
A. The Seiko 4R34 automatic movement provides approximately 41 hours of power reserve when fully wound. This means the watch can continue running for around 41 hours when it isn't being worn.
Q. Which Seiko 5 GMT Field Series colour should I choose?
A. That comes down to personal style. The green HDB001K has a more traditional Seiko field-watch look, while the ivory HDB002K offers a lighter and more distinctive appearance. As their main specifications are the same, dial colour is the biggest consideration when choosing between them.
