2025 Seiko 5 Sports SKX ‘Midi’ Mono 38mm Auto SRPK31K1

Here we have a 2025 Seiko 5 Sports SKX ‘Midi’ Mono 38mm Auto, reference SRPK31K1 (4R36-14B0), featuring a beautifully proportioned 38mm stainless steel case that sits comfortably on your wrist with thick, tapered lugs, a compact lug-to-lug length of 44mm, and a case thickness of 12.5mm to ensure a highly versatile and wearable daily fit. Polished and brushed surfaces transition with clean lines that honour the legendary SKX dive silhouette in a modern, downsized form factor. At 4 o’clock, a recessed push-pull crown is safely guarded by integrated case shoulders to maintain structural durability. The unidirectional rotating coin-edged bezel features a silver 60-minute scale on a black metallic insert, framing a flat Hardlex crystal positioned directly above a clean, monochromatic cream coloured dial. An outer minute track rehaut surrounds the applied black-outlined disc and baton indexes, heavily filled with LumiBrite to deliver exceptional low-light legibility. At 3 o’clock, a dual-language day-date window balances the dial, complemented by classic SKX-style hands filled with the same bright LumiBrite and a sweeping second hand with a circular counterweight. At noon, the modern Seiko 5 Sports '5' logo is proudly applied, while 'Automatic' completes the layout at 6 o'clock. On the reverse, a screw-down exhibition case back proudly displays the individual serial number. Beating inside is the ultra-reliable, in-house automatic Seiko Calibre 4R36 movement, featuring both hacking and hand-winding capabilities, operating with 24 jewels at 21,600 vibrations per hour. It comes paired with its original 20mm three-link stainless steel bracelet secured by a push-button three-fold deployant clasp with a safety lock; all links are provided. This watch comes complete with its Seiko presentation box, swing tag, and paperwork.

This watch is sold with its original Seiko box, swing tag and paperwork. It comes paired with its original 20mm three-link stainless steel bracelet secured by a push-button three-fold deployant clasp with a safety lock; all links are provided. The watch is from October 2025 and is sold in worn-and-enjoyed condition, as you can see. The watch comes with our 12-months Warranty.

I think Seiko absolutely nailed the proportions with this one. At 38mm, it captures everything that made the original SKX such a success, but in a size that feels right at home on almost any wrist. It's compact, comfortable, and one of those watches you can happily wear every single day. The monochromatic colourway is another huge plus. The cream dial paired with the silver bezel gives it a clean, understated look that feels a little more refined than the traditional SKX, while still retaining all of its tool-watch charm. It's subtle enough to wear with almost anything, yet distinctive enough to stand out from the crowd. For the price, I would not hesitate to add this to your collection today!

Reference : SRPK31K1 (4R36-14B0)
Movement : Automatic Seiko Cal. 4R36
Age : October 2025
Year : 2025
Case Size : 38mm
Case Thickness : 12.5mm
Lug to Lug : 44mm
Lugs : 20mm
Condition : Pre-Owned
Box and Papers : Box & Papers
Case Material : Stainless Steel
Warranty : 12-Months Warranty
The wrist model's wrist size is 7inch

Seiko's history began in 1881 when Kintaro Hattori established the K. Hattori retail and repair store. In 1892, Seikosha was established to make wall clocks. 1895 saw the production of their first pocket watch. 1913 saw the launch of their first wristwatch, the Laurel. In 1924, the first Seiko was manufactured. Daini Seikosha (now Seiko Instruments Inc.) was established in 1937. Seiko was listed on the Tokyo stock exchange in 1949. The Suwa factory became independent and formed Suwa Seikosha Co., Ltd. (now Seiko Epson Corporation in 1959). In 1956, Seiko launched Marvel as their first true in-house-made watch; they continued to make this watch until 1959. The Seiko Lord Marvel, introduced in 1958, was Seiko's first luxury watch, predating the well-known Grand Seiko. It was designed to rival Swiss brands with a refined design and higher specifications. In 1967, Seiko launched the calibre 5740C watch movement, a significant upgrade over the earlier calibre 5740A, which beat at 18,000, and the 5740B, which beat at 19800. This movement was special because it allowed the watch to run at a high speed of 36,000 beats per hour, making it Japan's first high-frequency watch. In fact, it was only the second watch movement of its kind in the world, following one released by a Swiss brand just a few months earlier. Japan’s first chronograph watch was introduced for the 1964 Tokyo Olympics; it was called the Seiko Crown Chronograph monopusher. Not stopping there, Seiko launched Japan's first true divers' watch, the Seiko Diver’s 150M, fitted with the automatic Calibre 6217, which was later given the nickname “62MAS” by collectors. King Seiko and Grand Seiko emerged as prominent lines within the Seiko brand, with King Seiko making its debut in 1961 as a distinguished luxury watch collection. Grand Seiko, on the other hand, has consistently set the standard for exceptional craftsmanship and precision engineering. In 1965, Seiko introduced a groundbreaking manual-wind movement featuring 25 jewels and hacking seconds, coinciding with the launch of the second-generation KSK series, which boasted sharp, angular cases and robust, flat-ended lugs. The King Seiko KCM was introduced in 1969, featuring a chronometer-certified movement that operates at an impressive 36,000 beats per hour, along with a sleek C-shaped stainless steel case. In 1975, the King and Grand Quartz brands were introduced, built at the Suwa Seikosha and Daini Seikosha factories. In 1977, a high-end Twin Quartz Cal. 92 was produced until 1979, when the 97KQ and 99KQ were introduced. The final 1981 King Quartz Cal. 94KQ movement remained in production until Seiko ended the King Seiko line in 1985. Despite the challenges during the Quartz crisis of the 1970s that led to the gradual shutdown of King Seiko production, Seiko made a comeback in 2022 by reintroducing the classic King Seiko collection. The company name was changed to the Seiko Corporation in 1990. Innovation at Seiko continues today with GPS Solar watches.