Thursday, March 15, 2018

Seiko Prospex “Mini-Turtle” SRPC37K1 (Similar with SRPC35K1, SRPC39K1 and SRPC41K1) – A Winning Design, A Review (plus Video)

Seiko ended 2017 with another take of the iconic 6309 diver of yesteryear. When the brand launched the Turtle re-craft edition back in 2016 under series reference SRP77x (I got the SRP773 in the collection. See the review here:, the Seikonistas went wild with excitement. Seiko quietly listened to feedback given and decided that some of the suggestions were valid. I guess the most grouse received must have been the size issue of the SRP77x series. A good proportion of the fan base found the Turtle too big for their wrist.

To address this problem, near the end of 2017, Seiko quietly launched another interpretation of the 6309. This new series is similar in capabilities to the 2016 series apart from its dimensions and a couple of small changes. Nicknamed “Mini-Turtle”, a lot of people gave positive reviews of this new iteration. This new series is not just a scaled down model but a new version of the 6309 icon. The series comprises of four models:


My choice is the SRPC37K1 because of its simplicity and real tool-like appearance. The all black dial and bezel closely resembles the original icon which was what I was going for.

The comparative statistics of the Turtle and Mini-Turtle are provided below.

Seiko Prospex Turtle Series 2016 (e.g. SRP773K1)
Seiko Prospex Mini-Turtle Series 2017 (e.g. SRPC37K1)
200 meter water rating
Screw-down crown and case-back
Unidirectional external bezel
Lumibrite paint
Width: 44.3 mm
Lug width: 22.0 mm
Lug-to-lug: 48.0 mm
Height: 14.0 mm
Width: 42.3 mm
Lug width: 20.0 mm
Lug-to-lug: 43.0 mm
Height: 13.0 mm
Recessed crown located at 4 o’clock
Non-recessed crown located at 3 o’clock
Flat Hardlex crystal
Flat Hardlex crystal with round magnifying Cyclops for the date aperture
Seiko 4R36 caliber
Seiko 4R35 caliber
Day and date complications
Date complication
Round shaped and Obelisk shaped hour markers
Pallet shaped and Mount shaped hour markers

The five most obvious changes are the smaller dimensions, the relocation of the crown, the elimination of the day complication, the addition of the magnifying glass and the use of the 4R35 caliber movement instead.

The change in dimensions is definitely a right move. It allows many more people to be able to wear the watch with confidence. Although it is fashionable (not at least) to wear larger watches, from a practical point of view, the 40.0 mm (±) is just the right size for most occasions. In this case, the SRPC37K1 fulfill this requirement admirable. In fact, one of the longest running dive watch by Seiko, the SKX007 is still in production even today (since 1996!). Despite it still using the old 7S26 movement, demand remains as buyers appreciate the comparatively smaller size compared to other contemporaries.   

The relocation of the crown is another positive for me. I prefer to see things on the watch to be symmetrically placed. Locating a crown at any other location apart from the four corners of the compass looks unbalanced in my view. For the SRPC37K1, it looks like a proper watch.

The elimination of the day complication reduces one visual cue from the dial in a good way. Honestly, I don’t find a day complication useful at all. Taking it away makes the dial look less cluttered.

The addition of the round magnifying glass (or Cyclops eye) on the flat Hardlex crystal is neither a hit or miss for me. Given the option, I would rather not have it. Like the crown location issue, this small bump on the crystal disrupts the symmetry of the watch somewhat.

The change in the caliber is purely because the elimination of the day complication. The overall core movement is still the 4R series caliber.

Overall, the changes are significant enough to classify this Mini-Turtle as a separate and unique diver watch line instead of just a smaller Turtle.

The Watch

Like the Turtle, the dial on the Mini-Turtle is generally similar yet gives a more homely feeling to an observer. The hour markers are slightly different; more like pellets and the aperture for the date is now similarly sized with the other markers. The addition of the magnifying glass above the date aperture provides a particular visual cue not found on the Turtle.

The only obvious changes on the dial itself are the smaller aperture for the date complication as well as the shape of the hour markers. The texts and logo on the SRPC37K1 is similar to the bigger Turtle.

The reduction in lug width to 20 mm is significant enough to change the aesthetic of the watch positively compared to its larger brother. Although the width of SRPC37K1’s watch face also reduced by 2 mm, in percentage, the reduction is just 4.5%. The percentage reduction lug width is a whopping 9.1% or twice that of the watch face. Due to this re-balancing, the persona of the Mini-Turtle is softer and more elegant in my view.

The watch is paired with a silicone strap with polished buckle and strap guide. The material is very soft and supple.

The crown is unsigned. From the bottom, you can see the threaded tube which raised the concern about the possibility of impact damage. However, on further inspection, it is noted that it would be extremely difficult to hit that particular point due to its location.

The bezel as well the solid screw-down case-back is similar to what you find on the bigger Turtle. However, the engine for the SRPC37K1 is the 4R35 by virtue of the elimination of the day wheel complication. Like the 4R36, this caliber operates at 21,600 bph (or 3 Hertz), it is an automatic movement with hand “windable” and seconds hand stop capabilities. It also has 41 hours of power reserve. With the elimination of the day wheel complication, the caliber only uses 23 jewels. Based on specifications, it is rated for an acceptable error of -35/+45 seconds a day. In reality, the actually performance is far superior.

Here is a photo of the watch in the dark.

As suggested earlier, the changes are significant enough to classify the Mini-Turtle as a separate and unique diver watch series instead of just a smaller Turtle. The actual design philosophy used by the Seiko designers are not publicly known and it was assumed to be “re-size the Turtle for smaller users”. However, the way the SRPC37K1 wears and its usability suggest that the design specifications may be more extensive than what was assumed.

I suspect Seiko has been getting a lot of feedback from its customers complaining about the brand perceived push toward bigger and bulkier sports watch designs. I believe a lot of brands have also been accused by their fans of disregarding smaller case sizes when designing new watches. Case in point is the Oris Watch Company. In recent years the brand has been making large watches but suddenly it decided to re-launch their iconic vintage Oris 65 dive watch and sales have exceeded expectations.

Similarly, when Seiko decided to re-launch their old 62MAS styled divers in the form of the SLA017 (see: and SBDC053 (see: recently, demand for these styles of watches spiked.

Anyway, if the Mini-Turtle is supposed to be a “her” of a “his and her” pairing to the Turtle, the crown should at least be located at the same position i.e. at 4 o’clock instead of 3 o’clock. Seiko would also not have eliminated the day wheel and added a magnifying glass. These are obvious indicators that we are looking at a new branch of dive watches from Seiko.

The Purchase Price

The suggested retail price in Malaysia is RM1,791.40. I was able to get it for RM1,200 and I bought it from my trusted AD in Mid Valley, Megamall. The serial number on the watch is 7D1108.

The Unboxing

Surprisingly, the watch box for this watch is rather dated in design, very unlike the more modern Prospex models. It still uses the old white square box with flat angled sides with silver trimmings along the middle where the box split into two. Internally, the watch sits on a large white pillow. All the accompanying documents are located inside the outer packaging box made out of white cardboard.  

The Wearing Experience

The SRPC37K1 wears more comfortably than its bigger brother. The smaller size allows it to sit firmly on the wrist especially for those with smaller hands. The experience one feel wearing the Mini-Turtle vis-à-vis Turtle is akin to the experience of wearing the SKX007 vis-à-vis the Monster.


As you can see from the comparative photos above (I do own all the four watches), the size difference makes smaller timepiece lighter, more manageable, more utility and with less aggressive stance compared to the bigger sibling.

Below is some photos of the watch on my wrist as well a video of the same.


I am starting to appreciate smaller cased sports watches. I realized the environment that I am usually in does not require an extreme designed watch to be on my wrist. Size and bulk are meant to impress but subtlety and detail can also achieve the same thing.

In this regard, the SPRC37K1 has not only reached the same level of satisfaction as the Turtle series but raised the bar further. This is definitely a winning design.

Watch Gallery


  1. This comment has been removed by the author.

  2. Very nice review, as usual. Your point about the magnifying date cyclop, I think the same as I own an Invicta grand diver 1st generation (seiko nh35a). I would prefer not having it, but this watch is in fact a knock off of the great Rolex submariner and I think many brands are imitating this design on their divers watch as it has now become an icon.

  3. hi friend.

    i google to find this watch and suddently i saw your review about mini turtle. yesterday i went to IOI putrajaya and price was rm 1700++.

    may i know which store at Mid Valley?

  4. What is the weight of the seiko mini turtle? Based on the 4 watches you have, mini turtle, turtle, skx007 and seiko monster, which is the smallest and lightest?

  5. Great watch! I also own one, same color as you. Been playing with different coloured nato straps. Im very satisfied with this model. The size is just perfect for medium sized wrist like mine. In my opinion, wear the same like SKX (I also own this model), but with the handy manual wind feature. My only hope it has day complication, then it will be perfect for me.

  6. I have the PADI version, bought at Pertama.

    Definitely a keeper, but could you kindly recommend a Seiko modder in KL who could help replace the existing crystal with sapphire?


    1. Sorry, not into modding. However, you can try some of the watch smiths shops in AmCorp mall.



Any contributions is appreciated!