Seiko SKX007 vs SRPD55 vs SSK001
The discontinued SKX007, the Seiko 5 Sports SRPD55 that took its look, and the SSK001 GMT version of the same case.
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The short answer
All three share a 42.5 mm case and 22 mm lugs. The SKX007 is the discontinued original with a 200 m rating and the 7S26 calibre. The SRPD55 is today's cheapest way into the look ($350 (US list)), with the 4R36 (hacking and hand-winding per Seiko) but only 100 m. The SSK001 adds a GMT hand via the 4R34 for $495 (US list).
Side-by-side specs
| Spec | Seiko SKX007 | Seiko SRPD55 | Seiko SSK001 |
|---|---|---|---|
| Case diameter | 42.5 mm | 42.5 mm | 42.5 mm |
| Thickness | 13.25 mm | 13.4 mm | 13.6 mm |
| Lug-to-lug | Not published by Seiko | 46 mm | 46 mm |
| Lug width | 22 mm | 22 mm | 22 mm |
| Calibre | 7S26 | 4R36 | 4R34 |
| Movement | Automatic | Automatic | Automatic |
| Power reserve | 41 h | 41 h | 41 h |
| Hacking seconds | Not stated | Yes | Yes |
| Water resistance | 200 m | 100 m | 100 m |
| Crystal | Hardlex (Seiko mineral) | Hardlex (mineral) | Hardlex (mineral) |
| Case material | Stainless steel | Stainless steel | Stainless steel |
| Ships on | Not stated | Bracelet | Bracelet |
| Weight | Not published by Seiko | 170 g | 161 g |
| US list price | Not stated | $350 (US list) | $495 (US list) |
| Status | Discontinued | In production | In production |
| Suits wrists of about our sizing guide | 17.0–18.9 cm | 17.0–18.9 cm | 17.0–18.9 cm |
Specs summarised in our own words from the brand's product pages: SRPD55 source (checked 29 Oct 2026) SSK001 source (checked 23 Oct 2026). "Not published" means the brand page we checked doesn't list it, so we leave it blank rather than guess.
Wrist fit
Lug-to-lug (tip of the top lugs to tip of the bottom lugs) decides whether a watch overhangs your wrist more than the diameter does. Enter your wrist to see how each one should wear.
- Seiko SKX007 –
- Seiko SRPD55 –
- Seiko SSK001 –
Same rule of thumb as Watch Finder: case diameter of about 23.5% of your wrist circumference (−2 mm to +2.5 mm), and lug-to-lug no longer than about 29% of it plus 1 mm. A guide, not a rule; flat or round wrists differ.
Strap and lug-width fit
- Seiko SKX007: 22 mm lugs, ships on a strap or bracelet
- Seiko SRPD55: 22 mm lugs, ships on bracelet
- Seiko SSK001: 22 mm lugs, ships on bracelet
All of these share the same lug width, so straps move between them freely. Seiko does not publish spring-bar diameter or a strap code, so check the hole size on any aftermarket strap. More in our Seiko 5 Sports strap guide and the Seiko lug width chart.
Which should you buy?
It is the only one rated to 200 m. The other two are 100 m, fine for swimming but not a dive rating.
$350 (US list) list with a day-date, hacking and hand-winding.
The 4R34 adds a GMT hand for a second time zone.
All three take 22 mm straps, so a strap collection works across them.
Prices and where to buy
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Questions
Is the SRPD55 the same size as the SKX007?
Nearly. Both are 42.5 mm across. The SRPD55 is 13.4 mm thick with a published 46 mm lug-to-lug; our SKX007 source lists 13.25 mm and no lug-to-lug.
Is the SKX007 discontinued?
Yes. It is no longer in production, so prices depend on the pre-owned market and condition.
Can you swim with the SRPD55?
Yes. It is rated to 100 m, which suits swimming, but it isn't a dive-rated watch.
What lug width do they take?
22 mm for all three.
What does the SSK001 add?
A GMT hand driven by the 4R34 automatic calibre, so you can track a second time zone.
Watch.co is independent and not affiliated with any brand. We haven't handled these watches for this page: everything here comes from brand-published specs and our own analysis. Brand names are used only to identify products.