Released in 1992, the Cal. 0731 with design code 641 was part of Seiko's domestic market collection. Powered by the 0731 caliber with 29j jewels beating at 21,600 bph, it delivers a 36 hours power reserve. [seikata-wm-d5e9f4ff03b7]
Also known as: Sumo, Baby Tuna
