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Seiko 5 Sports SRPK20 Men's Watch – 42.5mm Blue Dial Stainless Steel
Ref. SRPK20
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The SRPK20 sits at 42.5mm across and 13.4mm thick, with a round stainless steel case finished in gold PVD coating. The blue dial carries sub-dials for day and date alongside hours, minutes, and seconds, with LumiBrite hands and markers for low-light legibility. A Hardlex crystal sits above the dial, while a uni-directional rotating black bezel with gold-tone accents frames the watch at the top. The bracelet is stainless steel with a matching gold finish, fastening via a tri-fold push-button clasp with lock. Lug width is 22mm. The 4R36 automatic movement includes hacking seconds and winds through wrist motion. Water resistance is rated to 100 metres.
- Reference
- SRPK20
- Brand
- Seiko
- Case size
- 42.5mm
- Case material
- Gold PVD
- Case shape
- Round
- Dial
- Blue
- Crystal
- Hardlex
- Bezel
- Unidirectional rotating
- Movement
- Automatic
- Calibre
- 4R36
- Functions
- Date
- Water resistance
- 100m
- Bracelet / strap
- Stainless steel bracelet
- Strap colour
- Gold
- Clasp
- Three-fold clasp
- Lume
- LumiBrite
- Retailer
- Watch Enclave
Learn more about Seiko
Kintaro Hattori opened a watch and clock shop in Tokyo in 1881, aged twenty-one, and began manufacturing under the name Seikosha — roughly, house of exquisite workmanship — in 1892. The Seiko name appeared on watches from 1924.
The company's significance is that it broke the Swiss monopoly twice. First on precision: Seiko was appointed official timekeeper of the 1964 Tokyo Olympics and built the quartz chronometers and printing timers to do it, and in the 1960s its movements placed highly at the Neuchâtel and Geneva observatory trials against the best Swiss houses.
Then on technology. On Christmas Day 1969 Seiko released the Astron, the world's first quartz wristwatch, accurate to five seconds a month where mechanical watches managed that per day. The consequences for Switzerland were catastrophic — employment in the Swiss industry fell by roughly two-thirds over the following decade. Seiko deliberately did not enforce its quartz patents, allowing the technology to spread.
The same year it produced the 6139, among the first automatic chronographs, and it has since introduced Kinetic, Spring Drive — a hybrid regulating a mechanical mainspring electronically, giving a perfectly gliding seconds hand — and its own dive and field lines.
Seiko remains fully vertically integrated, making its own hairsprings, quartz crystals, and even the Zaratsu-polished cases, at price points from under a hundred pounds upward.
- 1881
- Kintaro Hattori opens his Tokyo shop.
- 1924
- The first watches carry the Seiko name.
- 1964
- Official timekeeper of the Tokyo Olympics.
- 1969
- The Astron becomes the first quartz wristwatch.
- 1999
- Spring Drive enters production.
Also in 4 collections
This watch appears in Automatic Watches (1,718), Blue Dial Watches (857), Gold Watches (663) and Automatic Watches Under £500 (359).
Temporarily out of stock
Watch Enclave is not currently taking orders for this reference. Last listed as available on 19 August 2026. Stock is checked nightly and this page updates when it returns.
What the specifications mean
A mechanical watch for everyday wear.
Strengths
- 100m water resistance covers swimming and watersports
- Luminous hands and markers for low light
- Sits in the lower half of Seiko's range as we list it
Seiko 5 Sports SRPK20 alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | SRPK20 | R8823124002 | NJ0125-11E |
|---|---|---|---|
| Price | £339 | £339 | £319 |
| Case size | 42.5mm | 42mm | 43mm |
| Water resistance | 100m | 100m | 100m |
| Movement | Automatic | Automatic | Automatic |
| Strap | Stainless steel bracelet | Stainless steel bracelet | Rubber strap |
| Power reserve | — | — | 42 hours |
| This watch | Closely matched | Closely matched |
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 100m it is rated for swimming and snorkelling, though not for diving.
Water resistance explainedWill the glass scratch?
It resists most everyday knocks. Hardlex is a hardened mineral glass — tougher than standard mineral, softer than sapphire.
Sapphire, mineral and acrylic comparedDoes it need a battery?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
Quartz, automatic and solar comparedIs it a men's or women's watch?
Listed as men's.
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