Seiko Prospex Monster – SRP581K


The Seiko Monster is probably the Seiko watch with the most number of variants and has been feature many times on this blog. As we know, the regular Monsters come under the Superior line and are powered by the 4R36 movement. This time round, Seiko decided to release new variants under the Prospex line. These variants are not much different from the Superior ones except they had the Prospex logo on the dial and caseback.

Here are some photos of the SRP581K.







The caseback is very similar to the regular 4R monster except it has the Prospex logo and lack the inverted “U” (anti-magnetic) sign.


Below is a caseback shot of a regular 4R monster, SRP313K.


The Monster has 20mm lug width and its rubber strap always come with the word “Seiko” on it.


Here are the hang tags. The watch is distributed in Singapore by Thong Sia Co.



Price (SGD) is for reference only. Please do not contact me to buy.


Seiko SRP581K featured in this post is provided by:
Authorized Seiko dealer
K2 Watch Company

845 Geylang Road, Tanjong Katong Complex
#03-K1. Singapore 400845
Tel: 6746 0270

14 thoughts on “Seiko Prospex Monster – SRP581K

  1. I’m please that Seiko has done away with the chromed scallops on the sides of the case. However, I’m not enamoured with this new model or the SRP monsters in general. The shark tooth markers aren’t very original and the crown seems mismatched to the bezel. Much like the Samurai, the crown on the gen 1 monster felt like it fit.


  2. Looks more like a budget watch despite the Prospex moniker. Seiko should really, really make their dive watches 45mm or more. They are generally well-made but seriously lack presence on the wrists.


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  7. Hi Everybody, I’m happy to disagree with the critics of this watch 🙂 I purchased it a few days ago and am very satisfied. The frown upon small size leading to a “lack of presence on the wrist” is for me actually a great advantage and the exact reason I bought this model, and not any other of the Monster series. The others, while looking seriously cool, were simply waaaay too big for my small wrists, as are very many diver-styled watches nowadays. So, I’m very thankful to Seiko for making the watch relatively small. As for the feel – it does feel robust, the shiny finish I had been a bit wary of actually turned out nice as well, and the tooling is precise. It’s not an elegant watch, but it’s really easy to like. Ain’t it a beautiful world where even the weirdest tastes can be satisfied?


  8. For the srp307. Ive seen superior models and the prospex models. Can’t seem to find any difference even after reading some forums. Someone mentioned that in the prospex version, the scalloping where the case meets the bezel is now gone. I don’t exactly get what it means and by online images I can’t tell any difference.


  9. I own an Orange Monster 2nd Gen with steel strap. Very happy with it and it seems to have appreciated in value going by the used prices in eBay. It definitely has presence given its size and chunky shape. So far I am happy wearing it together with my SKX009.


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