Customer Review

628 of 648 people found the following review helpful
5.0 out of 5 stars Great engineered product, June 14, 2008
Verified Purchase(What's this?)
I am still in the process of reviewing this product. Here's what I have so far:

Xbar 107 seconds/week (runs fast) (7 min./month compared to 2-4 sec./month quart watch)
St DEV 27 sec.
N = 7
95% CI 2.447 using Student's t
m+ = 136 seconds/week
m- = 78 seconds/week


Good points:
* Beautiful with dark blue face, white symbols, functional medium blue nylon band;
* Easy to read, even in the dark;
* Easy to use with uncomplicated settings similar to other watches;
* Compact design;
* Measurement consistency is excellent compared to quartz mechanism.

Bad points:
* Difficult to set time (see instruction below);
* Gains 10 seconds a day (consistency); and
* Does not have a manual wind stem.

This watch looks great. Unlike other self-winding or kinetic watches, this one is compact. In the best tradition of Japanese product development they thought hard on how this watch should function and say about the wearer. The hands are easy to reading, even for those of use with failing eyesight. The second sweep hand has a read tip allowing easy setting of the time.

Unlike some Japanese product, they provided a short, simple instruction on winding the watch. Here, I am comparing them to Citizen's ecco-drive watch, which I also own. Just gently work your arm back and forth for three minutes and the self-wind watch will charge; or, you could wear it for a day.

Okay, now for the negatives. First, this is not your quartz watch. The original self-winding mechanism was invented, according to Wikipedia, by a Swiss watchmaker in 1770. Since then it has gone through several improvements but is not as accurate as the quartz mechanism popularized starting in the 1970's. Sieko warns that this watch could be off by as much as 10 seconds a day. One days use indicates that my watch runs about 10 seconds fast.

The great watchmaker Harrison, who invented the first chronometer accurate enough to track longitude, said that consistency is more important than accuracy. (A poor copy of one of Harrison's chronometers was carried by Captain Cook on his circumnavigation of the globe. He had nothing but good things to say about it.) I have another self-winding watch, an Armitron, which runs consistently 15 seconds fast on days that I wear it.

From my measurements of quartz watches, their accuracy, while dazzling when compared to old hand-wound watches, are less accurate than my old German pendulum clock. So I am told, the longer the arm, the more stable the swing and the more accurate the timepiece. I compare everything to atomic time. And, because the quartz mechanism is battery-driven, it seems to suffer from inconsistency. I carefully measured my collection of six quartz watches over a 2 year period. While the battery was new, the error was consistent. As the battery burned out, the error became difficult to predict. Sometimes a positive error (adding time) would become a negative error (losing time) as the battery died. This dying period was also hard to predict.

The accuracy of the quartz mechanism is not as good as my pendulum clock. They all lost or gained approximately 2-3 seconds, on average, per month.

Based on a week of measurements with the Armitron, I would say that it is shockingly inaccurate but consistently so. Assuming that the Sieko error continues to be consistently 10 seconds fast this will mean that I will have to reset it every week. This is a small price to pay for an otherwise beautifully crafted and honestly-priced handiwork.

Setting time
The date and day are fairly easy. I suggest turning the watch arms until the click past a day so you won't be twelve hours off.

Setting the time is another matter. What works best is to set the hour and minute hands, then gently hold the second hand. It should pulse a little as it tries to force itself forward. Once the seconds are accurate, release and the second hand should be accurate. It takes a little practice at first and don't set the time until you pump the watch 3 minutes to charge the spring.

Time to unwind
It takes about 39 hours (1 test) to unwind.

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Tracked by 1 customer

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Showing 1-10 of 11 posts in this discussion
Initial post: Aug 11, 2008 8:00:31 PM PDT
It takes about 39 hours to completely unwind and stop.


Posted on May 18, 2009 4:44:49 AM PDT
Zoltan says:
Thank you for a very good review!

Posted on Feb 1, 2011 8:05:02 AM PST
A. WANG says:
This watch is made in China as stated on the box when I received it.

In reply to an earlier post on Mar 28, 2011 6:36:52 AM PDT
A Reader says:
One needs to read these things very carefully. Possible only the box was made in china, the watch case in another place, the interior mechanism in yet another country.

Posted on Aug 11, 2011 7:07:06 PM PDT
[Customers don't think this post adds to the discussion. Show post anyway. Show all unhelpful posts.]

In reply to an earlier post on Oct 5, 2011 5:08:50 PM PDT
A. Davie says:
Have you found that 100m water resistant phone yet? ;)

In reply to an earlier post on Jan 16, 2012 2:52:48 PM PST
xwchen says:
Seiko SNK80*K2, the last "K" in "K2" of the model numbers means it was assembled in Korea according to the explanations in

Posted on Jul 23, 2013 3:10:21 PM PDT
David Staub says:
"Does not have a manual wind stem."??

In the product description on this web page, it reads as follows.

[. . . . or manually wind the main spring by turning the crown. . . . ]

In reply to an earlier post on Jul 23, 2013 3:38:36 PM PDT
No, Either wear it every day or wind it for 2 minutes every day. I usually just re-set it on use.

In reply to an earlier post on Jul 27, 2013 7:35:54 AM PDT
Sidarth Kher says:
no k is malaysia, and j is japan

the 2 refers to the band style(metal/fabric/nylon etc..)
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Review Details

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Location: Chicago, IL

Top Reviewer Ranking: 2,459