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1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesSeiko’s official pages identify SRPK29 and SRPK31 as watches in the 5 Sports SKX series. Both share the same published headline dimensions: a 38.0 mm case diameter, 44.2 mm lug-to-lug length and 12.1 mm thickness. Those figures make it possible to compare these two models, but they do not decode every SRPK reference: Seiko’s pages do not publish a universal key for the letters and digits.
How do you read Seiko SRPK model numbers?
SRPK29 and SRPK31 are complete reference names for individual Seiko 5 Sports SKX-series products. The official product pages establish which watches those references identify, but do not explain a general formula for “SRPK,” the following digits or suffixes such as K1 across the full range.
| # | Preview | Product | Price | |
|---|---|---|---|---|
| 1 |
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SEIKO SRPK18 Automatic Watch for Men - 5 Sports Collection - Men's Sport Watch, Stainless Steel with... | $328.95 | Buy on Amazon |
| 2 |
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SEIKO Men's SRPK97 5 Sports Watch | $380.00 | Buy on Amazon |
| 3 |
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SEIKO Men's SRPK87 5 Sports Watch | $310.00 | Buy on Amazon |
| 4 |
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Seiko 5 Sports Men's Watch SRPK67K1, Silver., Classic | $321.67 | Buy on Amazon |
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For identification, match the complete reference shown in a watch listing or on the watch to the corresponding manufacturer product page. Do not assume that a particular letter or digit always indicates a color, market, strap or case size; verify the dimensions and specifications for the exact reference.
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What size are the SRPK29 and SRPK31?
Seiko lists the same three headline dimensions for both models. Diameter is the case measurement across; lug-to-lug is the length from one end of the lugs to the other; thickness is the case height. Lug-to-lug and thickness add useful context that diameter alone does not provide when considering how a watch may wear.
#1 Best Overall
- RICH BLACK DIAL: this men's automatic watch features a rich black dial framed by a rotating elapsed timing bezel, features luminous hands and date calendar
- AUTOMATIC: these self-winding, automatic men's watches are powered by your movement, with a power reserve of 41 hours
- STAINLESS STEEL GOLD FINISH: features a durable stainless steel watch case and bracelet with luxurious gold finish and see-through caseback
- WATER-RESISTANT: these men's wrist watches are water-resistant down to 100 meters
- 4R36 CALIBER: equipped with the reliable caliber 4R36 automatic movement, this accurate men's watch keeps precise time
| Reference | Official series label | Diameter | Lug-to-lug | Thickness | Other listed specifications |
|---|---|---|---|---|---|
| SRPK29 | 5 Sports SKX series | 38.0 mm | 44.2 mm | 12.1 mm | Caliber 4R36; approximately 41-hour power reserve; 20 mm lug spacing; 10 bar water resistance; 140 g. Seiko Australia product page. |
| SRPK31 | 5 Sports SKX series | 38.0 mm | 44.2 mm | 12.1 mm | Caliber 4R36; approximately 41-hour power reserve; 10 bar water resistance; 140 g. Seiko UK product page. |
The measurements are manufacturer specifications, not a guarantee of fit on every wrist. They establish that these two references have matching published dimensions; do not assume other SRPK watches share them. Check each exact model page, including its regional version, before comparing another reference.
What is the difference between SRPK29 and SRPK31?
On the official pages cited above, the two models share the listed diameter, lug-to-lug length, thickness, caliber, approximate power reserve, water-resistance rating and weight. The SRPK29 page additionally states a 20 mm distance between the lugs. The cited pages do not establish a broader difference between the references beyond their individual product identities and listed details.
Rank #2
- SEIKO WATCH – Seiko SRPK97 wristwatch.
- SERIES – Seiko 5 Sports SKX series design.
- CRYSTAL – Curved Hardlex crystal.
- BEZEL – Unidirectional rotating bezel.
- WATCH DIAMETER – 42.5 mm.
What does the 4R36 movement offer?
Seiko identifies the SRPK29 and SRPK31 as using caliber 4R36. Seiko’s instructions describe the 4R36 as an automatic movement with a manual-winding mechanism, day and date display, 24 jewels and more than approximately 41 hours of continuous operating time. See Seiko’s Cal. 4R35/36/37/38/39 instructions.
Will a 20 mm strap fit the SRPK29?
Seiko lists the SRPK29’s distance between the lugs as 20 mm, so 20 mm is the nominal strap width to look for. That measurement does not verify that every third-party strap will attach or fit properly. Check the strap’s attachment type and the seller’s compatibility information for the exact watch.
Rank #3
- SEIKO WATCH – Seiko SRPK87 wristwatch.
- SERIES – Seiko 5 Sports SNXS series design.
- CRYSTAL – Curved Hardlex crystal.
- MOVEMENT – Automatic movement.
- WATCH DIAMETER – 37.4 mm.
Does 10 bar water resistance make these dive-certified watches?
No such certification is established by the cited product specifications. Seiko lists 10 bar water resistance for both models; that figure alone, even alongside a rotating bezel, is not evidence that either watch is dive-certified.
Quick Recap
Rank #4
- The SRPK65K1 special edition watch takes up the model's iconic "Checker Flag" design. The words "SPECIAL EDITiON" are inscribed on the case back. This Analogue watch features a calendar function: Day-Date and is equipped with Luminous Hands and Luminous Numbers
- High quality Silver Stainless steel strap, measuring 21 cm in length and 21 mm in width, with a Fold over with push button clasp
- Case diameter: 42 mm,case thickness: 13 mm, case colour: Silver and dial colour: Black
- Water resistant: 10 bars -Weight: 170 g
- The watch is delivered in an original gift box and has a warranty of 2 years
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.
