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Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →The Seiko Prospex SRPE35K1 and SRPE37 share the same core dive-watch specifications, but the cited listings pair them with different looks and bands: the SRPE35K1 has a black dial and steel bracelet, while the SRPE37 has a white dial and black silicone strap. Both are listed with Seiko’s 4R35 automatic movement, a roughly 41-hour power reserve, sapphire crystal and 200 m diver’s water resistance. The practical choice is mainly dial, supplied band, fit and the price in your market.
SRPE35 vs. SRPE37: the key differences
| Specification | SRPE35K1 | SRPE37 |
|---|---|---|
| Model naming | Seiko Boutique UK calls it Prospex “King Samurai.” | Seiko US identifies it as Prospex Sea; naming varies by region and retailer. |
| Dial and supplied band | Black dial; stainless-steel bracelet with three-fold clasp, secure lock and extender. | White dial; black silicone strap. |
| Movement | Caliber 4R35 automatic; manual winding; 41-hour power reserve. | Caliber 4R35 automatic with manual winding; approximately 41-hour reserve; 23 jewels and stop-seconds listed. |
| Case dimensions | Stainless steel; 43.8 mm diameter, 12.8 mm thick and 48.7 mm long. | Stainless steel; 43.8 mm diameter, 12.8 mm thick and 48.7 mm lug-to-lug. |
| Crystal and bezel | Sapphire crystal with inner anti-reflective coating; unidirectional rotating bezel. | Sapphire crystal with inner anti-reflective coating; unidirectional rotating bezel. |
| Crown and water resistance | Screw-down crown; 20 bar diver’s water resistance. | Screw-down crown; 200 m / 660 ft diver’s water resistance. |
| Lug width | 22 mm. | 22 mm. |
| Displayed price and availability | £560 on Seiko Boutique UK; listed out of stock when checked on 8 October 2026. | USD 625 on Seiko’s US product page when checked on 8 October 2026. |
Specifications and displayed prices are from the respective Seiko Boutique UK SRPE35K1 listing and Seiko US SRPE37 listing. The UK and US amounts are regional page prices in different currencies, not a like-for-like price comparison or proof of a completed sale.
What “King Samurai” means for these references
Use the reference number to identify the configuration, since retailer naming is not uniform. Seiko Boutique UK labels the SRPE35K1 “Prospex ‘King Samurai’” and notes that “Samurai” is a fan nickname associated with the case’s angular shape. Seiko US lists the SRPE37 under Prospex Sea rather than using that label. The cited listings make the dial and supplied band the clearest quick identifiers: black and bracelet for SRPE35K1, white and silicone for SRPE37.
Shared movement and everyday operation
Both listings specify Seiko’s 4R35 automatic movement with manual winding and an approximately 41-hour power reserve. The SRPE37 listing additionally specifies 23 jewels and stop-seconds. The SRPE35 UK page lists a 41-hour reserve but does not state those two details there. Both references include a date display in the cited product specifications.
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#1 Best Overall
- Seiko Automatic with Hand-winding Movement Cal. 4R35, 23 Jewels
- Anti-reflective Sapphire with Cyclops lens
- Power Reserve approx. 41 hours
- Case Diameter: 43.8m mx 12.8mm
- Lumibrite hands and indexes
For a watch that is not worn for a day or more, the stated reserve gives a useful expectation, not a guarantee of timekeeping precision. The cited pages do not provide comparative accuracy measurements for the two references.
Case size and wrist fit
Both are listed at 43.8 mm across and 12.8 mm thick, with a 48.7 mm case length or lug-to-lug measurement. That last dimension matters alongside diameter: the distance from one end of the case to the other helps indicate how the watch may span a wrist. If possible, compare all three dimensions with a watch that already fits you rather than deciding by diameter alone.
Rank #2
- PADI SPECIAL EDITION: Men's Prospex Sea diver watch features PADI Special Edition details and a durable stainless-steel case.
- AUTOMATIC MOVEMENT: Seiko 4R35 automatic movement with manual winding, 23 jewels, stop-second function, date display, and approximately 41-hour power reserve.
- 200M DIVER'S WATCH: 200m/660ft diver's water resistance, screw-down crown, and screw case back support underwater use.
- SAPPHIRE CRYSTAL: Sapphire crystal with magnifier and inner anti-reflective coating provides enhanced clarity and scratch resistance.
- CERAMIC BEZEL & SILICONE BAND: Stainless-steel bezel with ceramic display and unidirectional rotation pairs with a flexible silicone band.
Both references have 22 mm lug spacing. That is a useful size when searching for a replacement band, but nominal width alone does not establish that a particular strap, bracelet, end link, spring bar or clasp will fit the case. Check compatibility against the exact reference and the attachment geometry before ordering.
Water resistance and dive-watch features
Seiko’s product pages list a unidirectional rotating bezel and screw-down crown for these watches. The SRPE35K1 is rated at 20 bar; the SRPE37 is stated as 200 m / 660 ft. Seiko USA describes the SRPE37 as following ISO standards for scuba diving. These are manufacturer specifications and descriptions, not independent test results or a report of hands-on evaluation.
Rank #3
- SEIKO WATCH – Seiko SRPL15 Prospex wristwatch.
- COLLECTION – Prospex design.
- CASE DESIGN – Prospex Mare model format.
- MODEL REFERENCE – SRPL15 identifies the specific model.
- WATCH DIAMETER – 41.7 mm.
Water resistance is a product rating, not a promise that any individual watch will remain watertight indefinitely. For actual diving, follow the manufacturer’s use and maintenance guidance and have seals checked as appropriate; do not rely on a watch with unknown service history solely because its model carries a diver’s rating.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Price, region and availability
On 8 October 2026, Seiko Boutique UK displayed the SRPE35K1 at £560 and marked it out of stock. Seiko’s US product page displayed the SRPE37 at USD 625. Those figures describe what the pages showed on that date; local taxes, retailer pricing, stock and regional variants can differ. Check the exact reference with a local seller before buying, especially if a listing uses “King Samurai” without showing the reference number.
Quick Recap
Rank #4
- Movement:Automatic winding(with manual winding)
- Size:48*46*13mm,Waterproof:200m
- Case Material: Stainless Steel; Strap Material: Urethane; Dial Window Material: Sapphire Crystal
- Warranty: 1 Year
- Accessories: Instruction manual (English), PADI special box
Which one should you choose?
- Choose the SRPE35K1 if you want the black-dial presentation and prefer the supplied steel bracelet.
- Choose the SRPE37 if you prefer a white dial and black silicone strap, or the US listing and availability suit your market.
- Compare fit first if 43.8 mm diameter, 12.8 mm thickness or 48.7 mm length could be near the limit for your wrist.
- Confirm the listing if you are comparing prices or looking for a replacement band: verify the reference, region, included band and current stock rather than relying on the nickname alone.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
