Quick Answer: The Seiko SKX is a legendary Japanese automatic dive watch series produced from 1996-2019. The SKX007 (black), SKX009 (Pepsi), and SKX013 (38mm) all feature ISO 6425 certification, 200m water resistance, and the 7S26 movement at 21,600 vph with 40-hour power reserve.
Now discontinued, the SKX commands $300-700 on the used market. This guide covers specifications, model differences, buying tips, and modern alternatives.
What Is the Seiko SKX?
The SKX was Seiko's entry-level ISO-certified dive watch, produced for 23 years with minimal changes. "SKX" comes from Seiko's reference system: "S" for Seiko, "K" for case type, "X" for diver.
Three models defined the series:
- SKX007: Black dial and bezel—the all-black classic
- SKX009: Blue/red "Pepsi" bezel with blue dial
- SKX013: 38mm mid-size version
Seiko SKX Specifications: Full Comparison Table
| Specification | SKX007 | SKX009 | SKX013 |
|---|---|---|---|
| Case Diameter | 42mm | 42mm | 38mm |
| Lug-to-Lug | 46mm | 46mm | 44mm |
| Thickness | 13.25mm | 13.25mm | 13mm |
| Lug Width | 22mm | 22mm | 20mm |
| Bezel | Black aluminum | Blue/red aluminum | Black aluminum |
| Dial | Matte black | Blue sunburst | Matte black |
| Movement | 7S26 (21,600 vph, 40hr reserve, no hacking/hand-winding) | ||
| Water Resistance | 200m / ISO 6425 certified | ||
| Crystal | Hardlex mineral | ||
| 2026 Used Price | $300-600 | $325-650 | $350-700 |
SKX007 vs SKX009: Which Should You Choose?
The SKX007 and SKX009 are functionally identical—only aesthetics differ:
Choose SKX007 if: You want maximum versatility. Black-on-black works with everything from wetsuits to office casual. It's the safer choice for a daily wearer.
Choose SKX009 if: You want classic dive watch character. The Pepsi bezel references 1960s dive watches and adds visual personality. Slightly higher resale value.
Choose SKX013 if: You have wrists under 6.5" or prefer vintage 38mm proportions. Same specs as SKX007 in a smaller package.
Seiko 7S26 Movement: Accuracy & Performance
Every SKX uses Seiko's 7S26 automatic caliber—built for reliability over refinement.
| 7S26 Specification | Details |
|---|---|
| Beat Rate | 21,600 vph (6 beats/second) |
| Power Reserve | ~40 hours |
| Jewels | 21 |
| Accuracy (factory spec) | -20/+40 sec/day |
| Accuracy (typical) | ±10-20 sec/day |
| Hacking | No |
| Hand-Winding | No |
| Service Cost | $50-100 |
The 7S26 lacks hacking and hand-winding—features standard on modern automatics. This was deliberate cost engineering, not oversight. Real-world accuracy typically settles around ±15 seconds/day after break-in.
Seiko SKX History: 1996-2019
Seiko launched the SKX in 1996 as successors to the 7002 divers. The goal: deliver a genuine tool watch that working divers could afford.
The SKX007 became the foundation of affordable dive watch culture. Military units adopted it. Dive instructors wore it. The watch proved itself from tropical reefs to arctic waters, earning reputation through reliability.
Production ran 23 years with minimal changes—remarkable in an industry obsessed with updates. When Seiko discontinued the line in 2019, used market prices immediately began climbing.
Why Is the Seiko SKX So Popular?
ISO 6425 Dive Certification
The SKX earned genuine ISO 6425 certification—testing for water resistance, shock resistance, and legibility in darkness. Many watches claim "diver" styling; the SKX actually met the standard.
Largest Mod Community in Watchmaking
The SKX spawned the biggest watch modification ecosystem ever. Its standardized case accepts countless aftermarket dials, hands, bezels, and crystals. This modifiability extended relevance well beyond production years.
Unbeatable Original Value
At $200 retail, the SKX offered ISO-certified diving, automatic movement, and proven reliability. Swiss alternatives cost 3-5x more for similar specs.
Is the Seiko SKX Worth Buying in 2026?
Buy the SKX If:
- You want heritage: No modern watch replicates the original SKX experience
- You'll mod it: SKX has more aftermarket parts than any alternative
- You're collecting Seiko: The SKX is essential for any serious collection
Skip the SKX If:
- You need hacking/hand-winding: Modern alternatives include these at lower prices
- You want warranty: Used market means no manufacturer protection
- Specs-per-dollar matters: $350 buys sapphire crystal and ceramic bezel in new watches
Seiko SKX Price Guide 2026
| Model | Good Condition | Excellent/NOS |
|---|---|---|
| SKX007 | $300-400 | $450-600 |
| SKX009 | $325-425 | $475-650 |
| SKX013 | $350-450 | $500-700 |
NOS = New Old Stock. Prices as of early 2026.
Where to Buy Used SKX
- WatchUSeek / Reddit r/Watchexchange: Peer verification, established sellers
- eBay: Largest selection; use authentication for $400+
- Chrono24: Buyer protection; prices 10-15% higher
What to Check Before Buying
- Movement: Request video of seconds sweep and date change
- Bezel: Should click cleanly, no play
- Crystal: Hardlex scratches easily; check for deep marks
- Caseback: Must show Seiko serial and wave pattern
- Crown: Should screw down smoothly
Best Seiko SKX Alternatives 2026
From Seiko
Seiko 5 Sports SRPD ($250-350): Official SKX replacement with 4R36 movement (hacking + hand-winding). Different case design, no ISO certification.
Seiko Prospex SPB ($500-800): Premium divers with 6R35 (70-hour reserve) and sapphire. Closest spiritual successor.
Third-Party Options
Orient Kamasu ($250-300): In-house automatic, sapphire, 200m. Strong value.
Islander ($300-400): Purpose-built SKX alternatives with NH36, sapphire, ceramic bezel.
SKYRIM Mod Submariner ($289): For enthusiasts who want SKX-level movement reliability with modern finishing. Uses Seiko NH35 (hacking + hand-winding), adds sapphire crystal and ceramic bezel—the upgrades SKX owners always wanted. A middle path between vintage hunting and mass-market alternatives.
SKX Modification Guide
Popular Mods
- Crystal: Sapphire eliminates Hardlex scratch vulnerability
- Bezel insert: Ceramic resists scratching better than aluminum
- Dial/hands: Hundreds of aftermarket options
- Movement: NH36 drops in directly, adds hacking + hand-winding
Modding vs. Collecting
Modifications reduce collectibility. Heavily modded SKX watches sell for less than stock examples. Keep original parts if you might sell later.
Frequently Asked Questions
Is the Seiko SKX a good watch?
Yes. ISO-certified dive capability, proven 7S26 movement, and 23 years of production history make it one of the most reliable affordable automatics ever made.
How accurate is the Seiko SKX?
Factory spec is -20/+40 sec/day. Real-world accuracy typically ±10-20 sec/day after break-in. Not chronometer-grade, but adequate for daily wear.
Why was the Seiko SKX discontinued?
Seiko replaced it with the SRPD series in 2019, upgrading to 4R36 movement with hacking/hand-winding. Manufacturing modernization, not design problems.
Can you still get a Seiko SKX serviced?
Yes. 7S26 parts remain widely available. Most watchmakers charge $50-100. NH35/NH36 also drops in as an upgrade.
What wrist size fits the SKX007?
42mm case with 46mm lug-to-lug fits 6.25"+ wrists comfortably. Under 6.5", consider the 38mm SKX013.
Is SKX007 or SKX009 more valuable?
SKX009 (Pepsi) typically commands 5-10% higher prices due to stronger collector demand for the classic blue/red colorway.
Conclusion
The Seiko SKX earned legendary status through ISO certification at accessible prices, 23 years of unchanged production, and the largest mod community in watchmaking.
Your next steps:
- Want authentic SKX? Check WatchUSeek or r/Watchexchange; budget $350-500
- Want SKX reliability, modern specs? Consider SRPD ($250-350) or mod builders using NH35 ($285-350)
- Planning to mod? Start with sapphire crystal and ceramic bezel
The SKX proved tool watch capability doesn't require luxury pricing. That lesson shaped affordable dive watches for a generation.
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