Seiko · Seiko 5 Sports, SKX series and Seiko 5 Sports, SKX series
Seiko SBSA281 vs Seiko SSK001
7 published specifications differ between these two, and 8 are identical. Every figure below is what the manufacturer states for that reference; nothing is inferred from the other watch.
What differs
| Specification | ||
|---|---|---|
| Thickness | 13.4 mm | 13.6 mm |
| Crystal | Curved Hardlex | Hardlex with magnified glass |
| Bezel | Unidirectional rotating bezel | Rotating bezel with 24-hour display |
| Case back | See-through and screw case back, engraved LIMITED EDITION and serial number | See-through and screw case back |
| Bracelet | Nylon band, length 225.0 mm, 22 mm between the lugs | 22 mm between the lugs |
| Calibre | 4R36 | 4R34 |
| Movement notes | Stop second hand function and day/date display. Magnetic resistance 4,800 A/m. LumiBrite on hands and indexes. Total weight 95.0 g. Limited edition of 2,000 pieces. No daily precision figure is published for this reference. | 24-hour hand for dual time display, stop second hand function and date display. Magnetic resistance 4,800 A/m. LumiBrite on hands and indexes. Total weight 161.0 g. No daily precision figure is published for this reference. |
What is identical
Worth knowing as much as the differences: these are the specifications you cannot use to tell the two apart.
- Case
- Stainless steel, 42.5 mm
- Diameter
- 42.5 mm
- Lug to lug
- 46 mm
- Lug width
- 22 mm
- Water resistance
- 10 bar
- Movement
- Automatic with manual winding
- Power reserve
- Approximately 41 hours
- Jewels
- 24
Stated for one, not the other
These rows cannot be compared, because one maker publishes the figure and the other does not. An empty cell is a gap in the manufacturer's documentation, not a gap in the watch — and not a licence to fill it in from the other column.
| Clasp | not stated | Three-fold clasp with push button release, with secure lock |
|---|
What the differences cost you
Each note below follows from the published figures in the tables above — what they mean for intake, for a listing, and for the handover. Nothing here estimates a price or a margin.
Different movements to verify and to service
The SBSA281 runs the 4R36 and the SSK001 the 4R34. Two consequences at intake: the service history that is normal for one calibre is not evidence about the other, and the calibre is the check that catches a movement swapped into the wrong case. Confirm the movement matches the reference rather than assuming it from the dial.
What to check on each
SBSA281
- Advance the day and the date separately and confirm both set cleanly. The 4R36 shows a day as well as a date, unlike the 4R34 in the same collection, and the day wheel is the part most often damaged by setting in the wrong window.
- Check the nylon strap for fraying at the spring bar holes and for a keeper that has stretched. It is the least durable component on the watch and the easiest for a seller to overlook.
- Photograph the engraved serial number on the case back and record it. The edition is 2,000 pieces and the number is part of the object on a collaboration piece.
SSK001
- Grade the crystal as Hardlex, not as sapphire. Hardlex scratches where sapphire would not, and those scratches can often be polished out, so a marked crystal here is a cheap fix rather than a replacement.
- Check the magnifier over the date for lifting at its edges. It is a separate element bonded to the crystal and it can detach, which is a fault a photograph rarely shows.
- Note that Seiko publishes no daily accuracy figure for this reference. Do not borrow the +25 to −15 quoted for the 6R calibres, and say in the listing that the maker does not state one.
Sources
- Seiko official product page for reference SBSA281 (Seiko 5 Sports, SKX series, DENHAM Limited Edition, limited edition of 2,000 pieces) - Caliber Number: 4R36; Movement Type: Automatic with manual winding; Power reserve: Approx. 41 hours; Jewels: 24; Case Material: Stainless steel; Case Size: Thickness:13.4mm; Diameter:42.5mm; Lug-to-lug:46.0mm; Crystal: Curved Hardlex; LumiBrite: LumiBrite on hands and index(es); Band Material: Nylon; Bracelet Length: 225.0; Distance between lugs: 22; Water Resistance: 10 bar; Magnetic Resistance: 4,800 A/m; Weight: 95.0g; Functions: Stop second hand function; Day/Date display; Features: LIMITED EDITION on the case back; Serial number engraved on the case back; Unidirectional rotating bezel; See-through & Screw case back — retrieved 2026-09-22
- Seiko official product page for reference SSK001 (Seiko 5 Sports, SKX series) - Caliber Number: 4R34; Movement Type: Automatic with manual winding; Power reserve: Approx. 41 hours; Jewels: 24; Case Material: Stainless steel; Case Size: Thickness:13.6mm; Diameter:42.5mm; Lug-to-lug:46.0mm; Crystal: Hardlex with magnified glass; LumiBrite: LumiBrite on hands and index(es); Clasp: Three-fold clasp with push button release; Distance between lugs: 22; Water Resistance: 10 bar; Magnetic Resistance: 4,800 A/m; Weight: 161.0g; Functions: 24-hour hand (dual time display function); Stop second hand function; Date display; Features: Rotating bezel (24-hour display); Three-fold clasp with secure lock; See-through & Screw case back — retrieved 2026-09-22
Not affiliated with Seiko. Specifications are read from each manufacturer's own published documentation on the dates shown and may change; the manufacturer's current documentation governs.