SEIKO 5 SPORTS SRPG35K1 AUTOMATIC FIELD SERIES MEN WATCH
SRPG35K1
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- Warranty 1 Year
The Seiko 5 Sports SRPG35K1 is the field watch in its plainest, most useful form: a black dial with Arabic numerals, a 24-hour inner scale, LumiBrite on every hand and marker, and a khaki nylon strap. Nothing on it exists for decoration. The bead-blasted stainless steel case measures 39.4mm across with a 48.1mm lug-to-lug span, which is the size range most wrists handle without thinking about it, and the whole watch weighs 77 grams.
It runs on Seiko's Calibre 4R36 — an automatic movement wound by the motion of your wrist, with 24 jewels, a 41-hour power reserve, hand-winding and a stop-seconds function for setting the time precisely. There is no battery anywhere in it. The case back is see-through so you can watch the movement work, the crystal is curved Hardlex, and it is rated to 100 metres. The 20mm lug width opens it to almost any strap you care to fit.
At a Glance
- BrandSeiko
- Collection5 Sports
- MovementCalibre 4R36 Automatic
- Case Size39.4mm
- DialBlack, Arabic Numerals
- Case MaterialStainless Steel, Bead-Blasted
- GlassCurved Hardlex
- Functions3 Hands + Day & Date
- Water Resistance100m (10 BAR)
- StrapKhaki Nylon, 20mm
- Weight77g
- Power ReserveApprox. 41 Hours
Why You'll Love It
- No battery, ever. The 4R36 winds itself from the movement of your wrist, and you can wind it by hand when it has been sitting. A mechanical watch you can keep running indefinitely with nothing but wear.
- 39.4mm with a 48.1mm lug-to-lug is close to the ideal field watch footprint — big enough to read instantly, small enough that it disappears under a sleeve.
- 77 grams on a nylon strap. This is one of the lightest automatics in the range, and it is the reason people who normally find mechanical watches heavy get on with this one.
- Stop-seconds and hand-winding. You can set it to the second against your phone, and you can wind it up from cold without shaking it — both things cheaper automatic movements often skip.
- The see-through case back turns an entry-level automatic into something you can actually watch working. It is the fastest way to understand why mechanical watches are interesting.
- 20mm lug width, which is the most common strap size there is. Leather, rubber, mesh, another NATO — this watch takes almost anything, and changes character completely each time.
- 100 metres of water resistance, so swimming and rain are not a consideration.
- The day and date are both on the dial. A small thing, but most field watches leave the day off and you notice its absence within a week.
Perfect For
- First Automatic Watch
- Everyday Wear
- Outdoors & Hiking
- Smaller Wrists
- Strap Swappers
- Military Styling
- Students
- Gift for Him
Key Features
- Calibre 4R36 automatic movement — 24 jewels, 21,600 vibrations per hour, and approximately 41 hours of power reserve from a full wind. Self-winding from wrist motion, with manual winding available.
- Stop second hand function — pulling the crown halts the seconds hand so you can set the time precisely against a reference, rather than approximately.
- See-through and screw case back — a display window onto the movement, in a screw-down case back that maintains the water resistance rating.
- Black dial with Arabic numerals and a 24-hour inner scale — the field watch layout, built for reading at a glance in poor light and for converting to 24-hour time without arithmetic.
- LumiBrite on hands and indexes — Seiko's luminous compound charges under light and reads clearly in the dark without drawing any power.
- Day and date display — both indications on the dial, set via the crown.
- Bead-blasted stainless steel case — a matte, non-reflective finish that hides everyday marks better than polished steel and suits the military brief.
- Curved Hardlex crystal — Seiko's own hardened mineral glass, more shatter-resistant than sapphire though less scratch-resistant.
- Khaki nylon strap with a 20mm lug width — washable, quick to dry, and sized to the most widely available strap width on the market.
- 100-metre water resistance and magnetic resistance of 4,800 A/m.
Technical Specifications
The Seiko 5 Sports SRPG35K1 is a 39.4mm automatic field watch powered by Calibre 4R36, with 24 jewels, 21,600 vibrations per hour and approximately 41 hours of power reserve. The bead-blasted stainless steel case measures 13.2mm thick and 48.1mm lug-to-lug at a total weight of 77 grams, with a see-through screw case back and a curved Hardlex crystal. It features a black dial with Arabic numerals and a 24-hour inner scale, LumiBrite on hands and indexes, a day and date display, hand-winding and stop-seconds functions, a khaki nylon strap on a 20mm lug width, magnetic resistance of 4,800 A/m, and 100-metre water resistance.
| Model Number | SRPG35K1 |
| Case Material | Stainless Steel, Bead-Blasted |
| Case Diameter | 39.4mm |
| Case Thickness | 13.2mm |
| Lug-to-Lug | 48.1mm |
| Lug Width | 20mm |
| Weight | 77g |
| Glass | Curved Hardlex |
| Caseback | See-Through, Screw Case Back |
| Crown | Pull Out |
| Water Resistance | 100 Metres (10 BAR) |
| Magnetic Resistance | 4,800 A/m |
| Colour | Black |
| Markers | Arabic Numerals, LumiBrite |
| Hands | LumiBrite (Hour, Minute, Seconds) |
| Inner Scale | 24-Hour |
| Calendar | Day of the Week + Date |
| Material | Nylon |
| Colour | Khaki |
| Lug Width | 20mm |
| Calibre | Seiko 4R36 |
| Type | Automatic (Self-Winding) |
| Jewels | 24 |
| Frequency | 21,600 Vibrations per Hour (3Hz) |
| Power Reserve | Approx. 41 Hours |
| Hand Winding | Yes |
| Stop Second Hand | Yes |
| Function | 3 Hands + Day & Date |
Best Matched With
- Olive Field Jacket
- White T-Shirt
- Chinos
- Dark Denim
- Flannel Shirt
- Canvas Sneakers
- Hiking Gear
Frequently Asked Questions
How does an automatic watch work — do I need to charge it?
No charging and no battery. A weighted rotor inside the movement spins as your wrist moves, winding the mainspring. Wearing it for a normal day keeps it running. If it stops after sitting unworn, wind it by hand — roughly 30 to 40 turns of the crown — and it will start again.
What happens if I do not wear it for a few days?
It stops. The 4R36 holds approximately 41 hours of power reserve from a full wind, so a watch taken off on Friday evening will typically have stopped by Sunday. Wind it by hand, reset the time, day and date, and carry on. This is normal for every mechanical watch and does not harm it.
How accurate is a mechanical watch compared to quartz?
Less accurate, and that is the trade. A mechanical movement gains or loses a number of seconds each day where a quartz watch would gain or lose that much in a month. In practice you reset it every week or two. What you get in exchange is a movement with no battery, no electronics, and a service life measured in decades. If second-perfect accuracy matters more to you than that, a solar quartz model is the better choice.
What is the stop second hand function for?
Pulling the crown out to the time-setting position halts the seconds hand. That lets you line the watch up to the second against your phone or another reference before pushing the crown back in, instead of getting the minutes right and the seconds approximately right.
Is Hardlex the same as sapphire?
No. Hardlex is Seiko's own hardened mineral glass. It resists shattering better than sapphire, which matters on a watch built for outdoor use, but it scratches more easily — sapphire rates 9 on the Mohs hardness scale and mineral glass sits well below that. If a scratch-free crystal is your priority, look at models specified with sapphire instead.
How does 39.4mm wear?
Comfortably across a wide range of wrists. The 48.1mm lug-to-lug is the number that matters more than diameter, and it is compact. The case is 13.2mm thick, which is tall for the size, so it sits more prominently than the diameter alone suggests — worth knowing if you wear fitted shirt cuffs. Try it on at any City Chain outlet.
Can I change the strap?
Yes, and this watch is a good candidate for it. The lug width is 20mm, the most widely available size, so leather, rubber, mesh and other NATO straps all fit. Changing to a different strap changes the watch's character more than you would expect from a black-dialled field watch.
Can I swim with it?
Yes. At 100-metre water resistance it handles swimming and recreational water activity. It is not a diver's watch and is not rated for scuba diving. Never operate the crown while the watch is wet, and make sure the crown is fully pushed in before it goes near water. The nylon strap dries quickly, but rinse it in fresh water after the sea or a pool.
How do I set the day and date?
Both are set from the crown's intermediate position, with the seconds hand still running. Avoid adjusting the date between roughly 9pm and 3am, when the movement's calendar mechanism is engaged and changing it can cause damage. Set the time forward past noon first if you need to confirm you are in the afternoon rather than the small hours.
Does a mechanical watch need servicing?
Yes, eventually. A mechanical movement runs on lubricated moving parts that wear over years of use, so a service every few years keeps it running to specification. City Chain can arrange servicing through Seiko's authorised service network — bring your warranty book.
Is this a good first automatic watch?
It is one of the more sensible entry points. The 4R36 is the same movement Seiko uses in considerably more expensive models, hand-winding and stop-seconds make it easy to live with, the see-through case back means you can see what you have bought, and the price of entry is low enough that experimenting with straps and wearing it hard both feel reasonable. Browse the full Seiko 5 collection.
What warranty does this watch come with?
The SRPG35K1 comes with a 3-year warranty when purchased from City Chain Singapore, an authorised Seiko retailer. Keep your warranty card and proof of purchase — both are required when submitting the watch for service.
Why Buy from City Chain Singapore
- Authorised Retailer 100% genuine Seiko product
- 3-Year Warranty Covered on every purchase
- Free Shipping All orders within Singapore
Extra $15OFF with min. $200 spend
Use Code: 15FORYOU
Extra $30OFF with min. $400 spend
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Calibre Type: Automatic - Powered By The Movement Of The Wearer
Calibre Number: 4R36
Calibre Function: Analogue - 3 Hands
Power Reserve: Approx. 41 Hours
Display: Analogue
Case Material: Stainless Steel
Case Color: Silver
Case Diameter: 39.4mm
Case Thickness: 13.2mm
Case Length: 48.1mm
Water Resistance: 100 Metres
Glass: Curved Hardlex
Crown: Pull Out
Rotating Bezel: N/A
Dial Color: Black
Dial Markers: Arabic Numerals
Hand Indicators: Hour, Minute, Seconds
Calendar Indicators: Date, Day of the Week
Lumibrite: Hands & Markers
Band/Bracelet: Strap - Nylon
Band Color: Khaki
Hand Winding: Yes
See-through Case Back: Yes
Delivery within Singapore | Order by 11AM
(Checkout options may vary depending on minimum order requirements)
• Free Standard Delivery (3 business days)
• Free Next Day Delivery
• Express Delivery at $30 (order by 2PM)
• Click & Collect (ready in 2–3 business days)
Weekend & Public Holiday Orders
Orders placed during this time will be processed on the next business day.
For online purchase, you can have bracelet or leather strap adjustments done at any City Chain store. Please bring along your warranty book for the service.
