Seiko Propsex King ‘Sumo’ Automatic Blue Dial Stainless Steel Bracelet Men’s Watch SPB321J1

This watch shape is affectionately named ‘Sumo’ by Seiko fans because of its size and shape and the 12 o’clock marker – it’s a substantially strong looking timepiece.

This latest design has been updated with new modern features, including a ceramic bezel and super hard coating on the case and bracelet for durability. A new 3 row bracelet has been specifically made for this model, while the clasp has also been modernised.

The dial features a fine pressed pattern dial with gradations of blue.

Prospex is a combination of the words 'Professional' and 'Specifications.' Seiko Prospex timepieces are designed to be practical, reliable and durable; to meet the high standards required in extreme environments for sports lovers and adventure seekers alike.

Since launching Japan’s first diver’s watch in 1965, Seiko’s innovative watchmaking has changed global dive watch standards.

The Case:

The Seiko Prospex ‘Sumo’ SPB321J1 is housed in a large case that measures 45mm in diameter and 12.9mm in height. The bulky proportions of the case are one theory suggested to explain the watch’s ‘Sumo’ moniker. One update to the SPB321 is that it is crafted out of stainless steel with Super-Hard coating, which improves the durability of the case. A further update is that the unidirectional rotating dark blue bezel insert is now made out of ceramic, as opposed to aluminum, which improves the longevity and resilience of the watch. It exhibits a 60-minute diving scale and a luminescent pip at the 60-minute mark. The case retains its twisted lugs with alternating polished bevels and brushed lines. The screw-down crown maintains its 4 o’clock position, whilst it also features a sapphire crystal like the previous generation of ‘Sumo’ did. 

The Dial:

Further developments to the ‘Sumo’ SPB321J1 are also present through the design of the dial, as it showcases a blue gradient effect which has a fine horizontal wave pattern. The dial does feature Sumo’s iconic markers and hands. The 12 o’clock marker features a unique marking which Seiko-fanatics have suggested bears a resemblance to the 'Mawashi' (the underwear worn by a Sumo during a match). The markers and hands are coated with Lumibrite, ensuring that the dial remains readable in the dark. A date-display window is located beside the 3 o’clock marker. 

The Bracelet:

The 3-link bracelet has also been redesigned, it is also made of stainless steel with a Super-Hard coating that has been treated to a fully brushed finish. It now features a fold over clasp with a secure lock, push-button release and wetsuit extension.

The Functions:

The Seiko ‘Sumo’ SPB321J1 is powered by Seiko’s 6R35 automatic movement, which has a 70-hour power reserve and has an accuracy of -15/+25 seconds per day. It is water resistant to 200 metres, which means that it can be worn when diving. 

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