Seiko · Presage Cocktail Time and Seiko 5 Sports, SKX series

Seiko SRE007J1 vs Seiko SSK001

13 published specifications differ between these two, and 1 are identical. Every figure below is what the manufacturer states for that reference; nothing is inferred from the other watch.

What differs

Specification	Seiko Cocktail Time, 2R05, 30.3 mm, dial with diamondsSRE007J1	Seiko 5 Sports SKX series GMT, 4R34, HardlexSSK001
Case	Stainless steel, 30.3 mm	Stainless steel, 42.5 mm
Diameter	30.3 mm	42.5 mm
Thickness	10.9 mm	13.6 mm
Lug to lug	37 mm	46 mm
Lug width	14 mm	22 mm
Water resistance	5 bar	10 bar
Crystal	Box-shaped Hardlex	Hardlex with magnified glass
Case back	Screw case back	See-through and screw case back
Bracelet	14 mm between the lugs	22 mm between the lugs
Calibre	2R05	4R34
Power reserve	Approximately 40 hours	Approximately 41 hours
Jewels	21	24
Movement notes	Stop second hand function and date display. Listed by Seiko as a women's model. No daily precision figure, LumiBrite line, clasp type or weight 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.

Movement: Automatic with manual winding

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.

Bezel	not stated	Rotating bezel with 24-hour display
Dial	Set with diamonds, as listed under the reference's features	not stated
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.

One of these is the harder fit

Lug to lug is 46 mm on the SSK001 against 37 mm on the SRE007J1 — a 9 mm difference across the wrist. Diameter is what buyers ask about; lug to lug is what decides whether a case sits flat or overhangs. Ask for a wrist measurement before shipping the SSK001, and put the figure in the listing rather than the diameter alone.

These reach different buyers

42.5 mm on the SSK001 against 30.3 mm on the SRE007J1. Diameter is a poor predictor of how a watch actually sits, but it is the field buyers filter on, so the two land in front of different people. Do not let one listing's photographs or copy stand in for the other.

A visible difference in how they wear

2.7 mm of thickness separates these, with the SSK001 the taller at 13.6 mm. That is the difference between a watch that goes under a cuff and one that catches on it — worth a photograph from the side rather than a number in a table.

Do not describe these the same way

The SRE007J1 is rated to 50 metres and the SSK001 to 100. A rating is a factory figure for a new watch with fresh gaskets, not a promise about a used one — but the gap still matters in writing. Describe the SRE007J1 in words a buyer can act on, and do not let a template carry the SSK001's language onto it.

What to check on each

SRE007J1

Count the set stones against a photograph of a known-correct example and check each one is seated and unchipped. A dial with stones is the one place on a watch where a missing component can be very small and very obvious.
Read the rating as 5 bar and describe it that way. It is the lowest figure of any Seiko documented here, and it is a rating for splashes rather than swimming.
Note the box-shaped Hardlex crystal. It stands proud of the case like a box sapphire but scratches like mineral glass, so it both takes knocks and can often be polished.

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

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.