Review of the Seiko SRP721K1

I purchased this watch in Sep 2016 from a friend after the purchase of my Seiko Turtle SRP 779.


I was always looking forward to purchase a cheap Seiko which had some use of exotic materials like carbon fibre. To me, the black/white and red colour scheme was appealing. To be honest, this was a fairly impulsive buy as it was just a month after my Seiko Turtle purchase. The SRP721K1 (46mm case and is 13mm thick) uses the upgraded Seiko 4R36 movement, unlike some of the other Seiko 5s. It has a carbon fibre dial and a carbon fibre strap as well. The watch is a simple time only watch with a second hand. I purchased this from a friend after he bought it from a watch boutique in Bangkok. The watch is one of the more advanced in the Seiko 5 range. Seiko is a renowned brand which needs no introduction whatsoever. This watch is a limited edition of 1000+ pieces and was only made for the Thai market. The Thai market is one of the top 3 markets for Seiko.


Seiko movements are reliable and are made in-house. The Seiko 4R36 mechanical movements has been around for ages and keep good time and chronometry. In addition, because they are Japanese movements, they are a lot more affordable. In fact, the 4R36s, 6R15s are comparable to Miyota movements or even Swiss ETAs. There is extensive lume on the SRP721K1, comparable to some of Seiko’s other divers. Seiko watches are good value-for-money and aesthetically pleasing and for good reason. In terms of price point, Seiko 5’s are very affordable and presents excellent value for those who are new to mechanical watches.

The main reason why I found it so attractive was the use of carbon fibre on the dial. My reasons are listed below:

The SRP721K1 comes in a stainless steel case with titanium carbide coating (about 49mm lug-to-lug) and a black leather strap with embossed carbon structure. This gives the watch an all-black appearance. I believe the titanium carbide coating is similar to DLC treatment that other watch brands use. The watch is quite substantial in terms of size on the wrist. The leather strap is of top quality and is very durable. It certainly can’t be found on other Seiko 5s. The pattern on the strap matches the dial and there isn’t a need to change straps.


Carbon fibre is largely made out of polyacrylonitrile (PAN), which is an organic polymer, characterized by long strings of molecules bound together by carbon atoms. This gives it a tensile strength that is greater than stainless steel. They are also more expensive to produce.

The watch is rare and doesn’t have much coverage online, given that it is a Limited Edition. Carbon fibre is a unique material in watch-making and is usually associated with being sporty. Brands like Hublot have experimented with this material. The dial is largely symmetrical, other than the day-date indication at 3 o’clock. The hour markers and minute markers are shaped like broad arrows. The dial is carbon fibre and black, with white fonts and markers. There is also a splash of red font on the words ‘Sports’, ‘Limited Edition’ and the counterbalance on the second hand. This gives the watch a more playful look. One thing I love is that the background of the date window matches the dial colour. Way to go, Seiko!


The SRP721K1 is a dive watch with 100 meters water resistance, without a screw-down crown. This watch can certainly be used for sports and for daily use. It will pair well with formal attire, like a suit/blazer or even t-shirts and jeans. I have worn this piece numerous times to work and I have had no trouble with it. Being 14mm tall, it might not slide under most shirt-cuffs. I would say that the watch is quite stealthy in nature due to the dull black colour on the dial and strap. The watch does not get as much wrist time as my Ball or Tudor watches as it also costs much less. The uni-directional bezel is also coated with the same titanium carbide coating and is easy to turn.


The watch uses the Seiko 4R36 automatic movement, which is hand winding and has hacking capabilities. This a certainly a workhorse movement that is widely used in other Seikos like the famous Prospex range. The movement comes with a 42 hour power reserve when fully wound. However, I am not used to watches which can’t wind and have to be powered via wrist movements. Hence, this watch suits me more than the SKX range. The movement is also sparsely decorated as can be seen from the display caseback. The rotor is also very quiet and barely audible. The watch seems to be fairly accurate based on the brief period which I had it with me.

SRP721K1 has Seiko’s renowned proprietary Hardlex crystal. It gives the watch greater presence and texture, evoking a vintage feel while claiming to be harder than hesalite crystal. Although not as superior to sapphire crystal in terms of scratch resistance properties, it is durable and decent enough.


Overall, I am impressed by how the watch looks. My main gripe was not that it is very large and almost over-hangs my wrist.  I have no issues with the weight of the watch. The Seiko SRP721K1 is a unique entry level dive watch which boasts the use of a unique material, carbon fibre. It is something that is highly recommended. The watch is not available in Singapore and retails for SGD 525. You may consider purchasing it online via eBay or Amazon. If you are considering an entry level dive watch, this watch might just be the one for you.




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