The Seiko Prospex 200M Automatic Sumo Ref. SBDC031 was initially released in 2007 is a professional dive watch. Powered by Seiko’s automatic caliber, 6R15, operating at 21,600 BPH (3 Hertzs). It has 23 jewels with a power reserve of 50 hours through a Spron 510 mainspring.

The 200m water resistant stainless steel case measure 44mm case without the crown. The bezel is aluminum and has large printed markings on it. It rotates smoothly in 120 positions has zero free play in a clockwise direction. Mixture of satin brush and high polishing is on the whole watch. Similar to the JDM models, the screw down crown at four o’clock is signed with an “S”.  The case does comes with lug holes allowing swapping of straps with ease.

The watch’s unique aesthetic along with the fat markers on the bezel earns this watch the nickname of “Sumo”. The hour markers and hands are coated with Seiko’s LumiBrite allowing it to glow brightly in the dark.