Choosing a Seiko 5 Sports watch can be harder than choosing the movement inside it. The collection offers plenty of variations on a dependable automatic formula, so specifications alone may not narrow the field very much. The new Seiko 5 Sports SKX series HDB004 and HDB005 illustrate that perfectly.
Price: £340 (About $459)
Where to Buy: Seiko
Mechanically, they are effectively the same watch. Both use Seiko’s 4R36 automatic movement, both have a 42.5mm stainless-steel case, both offer 10-bar water resistance, and both arrive on stainless-steel bracelets. The meaningful difference is visual.
The HDB004 pairs a silver-white dial with a black bezel and yellow-gold-tone details. The HDB005 goes in a completely different direction with green across its dial and bezel, complemented by rose-gold-tone accents.
That makes the buying decision unusually simple: You are not paying for a better movement or additional functionality in one model. You are choosing which interpretation of the Seiko 5 Sports formula you want to wear.
The HDB004 Is the More Contrasting Option
The HDB004 uses a pale silver-white dial surrounded by a black rotating bezel, while yellow-gold-tone hands and markers add warmer highlights.
That combination changes the personality of a case that otherwise retains familiar Seiko sports-watch proportions. The black bezel creates a strong visual boundary around the lighter dial, while the gold-tone details move the watch away from the purely utilitarian look associated with many black-and-steel sports watches.
Price: £340 (About $459)
Where to Buy: Seiko
Calling it dressier is still subjective. The HDB004 remains a large automatic sports watch with a rotating bezel and steel bracelet. What the design does accomplish is give buyers a lighter, higher-contrast alternative without changing the basic hardware underneath.
The HDB005 takes almost the opposite approach. Its green dial is paired with a matching green bezel, while rose-gold-tone hands and indexes provide contrast.
Those colorways should not be confused with functional differences. The two models share the same movement, dimensions, materials, and core capabilities.
For someone who already owns a conventional black, blue, or silver sports watch, the HDB005 is arguably the more distinctive addition to a collection.
The 4R36 Keeps Things Familiar
Both watches run Seiko’s well-established 4R36 automatic caliber, which can also be wound manually. The movement has 24 jewels, a stop-seconds function for more precise time setting, and a combined day/date display. Seiko rates the power reserve at approximately 41 hours.
Price: £340 (About $459)
Where to Buy: Seiko
That reserve is adequate for a watch worn regularly, but it is not especially generous by current mechanical-watch standards. If either model is left unworn through much of a weekend, it may have stopped by the time you return to it.
That does not make the 4R36 a poor choice. Its appeal is familiarity and straightforward functionality rather than technical novelty. These watches are not being positioned around a new movement, a longer reserve, or a higher published accuracy specification.
The visual redesign is the story.
These Are Still Full-Size Sports Watches
Both references measure 42.5mm in diameter, 14.2mm thick, and 46mm lug to lug.
The relatively controlled lug-to-lug measurement may help keep the case from extending too far across some wrists, but a 42.5mm diameter and 14.2mm thickness still put these firmly in substantial sports-watch territory.
They also weigh 169 grams on their steel bracelets. Buyers moving from a lightweight quartz watch or a smaller mechanical watch should expect a noticeably heavier package.
Seiko uses curved Hardlex for the crystal rather than sapphire. Hardlex is familiar across much of the Seiko 5 Sports range, but shoppers who prioritize maximum scratch resistance may still find sapphire-equipped alternatives more appealing.
The bracelet attaches across a 22mm lug width and uses a three-fold clasp with push-button release and a secure lock.
The SKX Look Comes With 10-Bar Water Resistance
The HDB004 and HDB005 sit within Seiko’s SKX series, which draws inspiration from one of the brand’s best-known sports-watch families. Both watches reinforce that connection with a unidirectional rotating bezel, strong luminous markers, and an overtly water-oriented appearance.
Seiko specifies 10-bar water resistance, or 100 meters.
That gives either watch useful everyday flexibility around water, but it is important not to turn the styling into a claim Seiko does not make. The company lists these under Seiko 5 Sports rather than its Prospex diving range.
Buyers specifically shopping for one of Seiko’s purpose-built diving watches should compare these against Prospex models rather than assuming the rotating bezel and SKX-series name make them equivalent.
Other practical specifications include 4,800 A/m magnetic resistance, LumiBrite on the hands and indexes, and a see-through screw caseback that leaves the 4R36 visible.
Who Should Buy the HDB004 or HDB005?
There is no mechanical winner between these two. Choose the HDB004 if you want stronger contrast between the dial and bezel and prefer yellow-gold-tone details against a lighter dial. It offers a more restrained way to make the familiar Seiko sports-watch shape look different.
Choose the HDB005 if color is the reason to buy another Seiko 5 Sports. The green dial and bezel, combined with rose-gold-tone details, give it a more immediately recognizable personality.
Both models are scheduled for release in October 2026. Seiko’s U.S. site currently lists the watches without an MSRP, while official regional pricing includes £340 in the UK, and CAD 550 in Canada. Buyers should wait for Seiko to confirm U.S. pricing.
Neither watch reinvents Seiko 5 Sports, and that is arguably the point. If you already like the 42.5mm case, 4R36 movement, day/date display, rotating bezel, and 10-bar water resistance, the HDB004 and HDB005 let you make the decision based almost entirely on personality.
Price: £340 (About $459)
Where to Buy: Seiko
The HDB004 is the sharper contrast. The HDB005 is the stronger color statement. Everything important underneath is the same.
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