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I did not want another quartz watch. I wanted something that winds as I walk, with a seconds hand that glides. That is the first-automatic itch. I shopped Amazon the way I always do: match the model, look at price and stock that day, then ask if I would actually wear it on a weekday.
Three live pieces. A Seiko 5 Sports I could add to cart. An Orient Kamasu that still looks like a diver-style daily. A Tissot PRX Powermatic 80 if I was ready to spend Swiss money on an integrated bracelet. Same homework. Different jobs.
Why These Three
Forums will send you down twenty references. I wanted three I could click. Sports, diver-style, and that 1970s integrated look. Bracelet on all three.
The pepsi SRPD I wanted was out of stock, so I used the live SRPD81. Same Seiko 5 Sports family. I would rather send you to a watch sitting in a cart than to an empty pepsi page.
The Kamasu is the one I open for sapphire and a real bezel. The PRX is the one I open for thinner steel and a waffle dial. If you wanted the PRX shape without the automatic, that is a different watch. Quartz PRX pieces were around $450 on Amazon when I looked.
How An Automatic Actually Behaves
An automatic winds from a rotor as you move. Wear it and it keeps going. Leave it in a drawer for a few days and it may stop. That is normal. Set the time and wear it again. Quartz is easier if you rotate five watches and forget this one for a week.
The Seiko and the Orient both mention manual winding. You can turn the crown instead of shaking the watch. The Orient also names hacking on the F6922, so the seconds hand stops when you pull the crown to set the time. I like that for matching a clock.
Power reserve is how long it can sit still and still run. The Tissot listing copy talks about 80 hours. Friday night off the wrist, still alive Monday morning if it was fully wound. The Kamasu page did not print a reserve number. Neither did the Seiko. I am not going to guess. Wear them. If they stop, wind them.
Water numbers are not scuba licenses. I treat 100 m as rain, a sink, and a pool with the crown set. I treat Amazon’s 200 m note on the Kamasu as more surface water, not a diving course. Rinse after salt or chlorine. Do not play with the crown in the water.
Seiko 5 Sports SRPD81
When I checked in early September, the SRPD81 was $450.00. Only one left in stock. 4.4 out of 5 from 96 ratings. I would not wait a week and assume it is still there.
42.5 mm. Automatic with manual winding. Exhibition back, so you can watch the rotor. Steel bracelet. Hardlex crystal. 100 m. A sports automatic, not a dress sliver and not a 200 m tool watch.
In my taste this is the “Seiko 5 on a bracelet, and I want to see the movement” pick. Hardlex will scratch sooner than sapphire. I know that going in. I would wear it to work and through weather. I would not pick it if I needed a rotating bezel or a thin integrated bracelet.
See the Seiko 5 Sports SRPD81 on Amazon
Orient Kamasu RA-AA0004E
When I checked in early September, the green Kamasu was $385.00. In stock. 4.4 out of 5 from 75 ratings. Cheapest of the three that day.
41.8 mm across. 46.8 mm lug-to-lug. 12.8 mm thick. 22 mm lugs. Those last numbers matter more than diameter on a short wrist. F6922 automatic with hand-winding and hacking. Day-date. 120-click bezel. Screw-down crown. Sapphire. Steel bracelet. 200 m on the listing, with Amazon’s own note that this is not for diving. Swim and surface sports. Not a scuba class.
In my taste this is the first automatic that still looks like a tool watch. Green dial. Bezel for a kitchen timer. Sapphire if you are clumsy around desks. It will wear thicker than the PRX. I like that trade for a daily beater. I would skip it if I wanted a slim office watch.
See the Orient Kamasu on Amazon
Tissot PRX Powermatic 80 Ice-Blue
When I checked in early September, the ice-blue Powermatic 80 was $850 new. In stock. 4.8 out of 5 from 100 ratings. Roughly double the Seiko. You are paying for the Swiss automatic, the shape, and the thinness. There is no bezel.
40 mm. 10.93 mm thick. Sapphire. 80-hour reserve in the listing copy. 100 m, which I treat as swim and shower, not scuba. Integrated steel bracelet. Ice-blue waffle dial. It wears smaller than the two Japanese sports watches because it is thinner and the lugs do not stick out like a diver.
This is taste. I like ice-blue on steel more than another black sports dial. If you wanted the shape without the automatic, that is a different watch. Quartz PRX pieces were around $450 when I looked. Same silhouette. Battery inside.
I would skip the PRX as a first watch if the budget is the Seiko or Orient neighborhood, or if I needed a rotating bezel. Buy it if the 1970s integrated look is the whole point.
See the Tissot PRX Powermatic 80 ice-blue on Amazon
How They Compare
Size, crystal, water, and the price I saw. That is enough.
| Seiko 5 Sports SRPD81 | Orient Kamasu | Tissot PRX Powermatic 80 | |
|---|---|---|---|
| Size I noted | 42.5 mm | 41.8 mm, 46.8 mm lug-to-lug, 12.8 mm thick | 40 mm, 10.93 mm thick |
| Crystal | Hardlex | Sapphire | Sapphire |
| Water | 100 m | 200 m, not for diving on Amazon’s note | 100 m, swim and shower |
| Price I saw | $450, one left | $385, in stock | $850 new, in stock |
Ratings when I checked: 4.4 from 96 on the Seiko, 4.4 from 75 on the Kamasu, 4.8 from 100 on the PRX. Stars are other people’s taste. The Kamasu names hacking, a screw-down crown, and a 120-click bezel. The Seiko has the exhibition back. The PRX has the 80-hour reserve in the copy I read.
Who Should Pick Which
This is preference. You cannot fail it.
I would take the Seiko if I wanted the Seiko 5 sports look, a caseback I can stare at, and a watch I will wear in rain without thinking. I would live with Hardlex. I would check stock the same day.
I would take the Kamasu if I wanted sapphire, a bezel, and a screw-down crown on a first mechanical. Green is the color I keep coming back to. I would measure my wrist against that 46.8 mm lug-to-lug.
I would take the PRX if the integrated bracelet is what I actually want, I like ice-blue, and $850 still felt reasonable for a Swiss automatic with jeans or a jacket. I would not buy the quartz cousin and tell myself it is the same thing.
If none of those sentences sound like you, wait.
Bottom Line
Three first automatics I could shop on Amazon in early September. Seiko 5 Sports SRPD81 at $450 because the pepsi I wanted was out of stock. Orient Kamasu at $385 if I wanted sapphire and a bezel. Tissot PRX Powermatic 80 ice-blue at $850 if I wanted the thin integrated look and that long reserve in the listing. I like all three for different days. I would buy the one that matches the clothes I already own, then re-check price and stock the morning I click buy.
Seiko 5 Sports SRPD81 · Orient Kamasu · Tissot PRX Powermatic 80 ice-blue
Affiliate note: I may earn a commission if you purchase through my link, at no extra cost to you. I am a participant in the Amazon Services LLC Associates Program. Prices and ratings are as listed on Amazon when I checked in early September 2026 and may change.