Seiko wristwatch model (7431-5150), a vintage quartz (battery-operated) watch. The serial number 340301 on the case back indicates it was manufactured in April 1983. Watch Information Model: Seiko (7431-5150) RO. Movement: Analog Quartz (Caliber 7431). Manufacture Date: April 1983. Case Back Material: Stainless Steel (ST. STEEL BACK). Case Material: NSA+NSCG codes indicate that parts of the case are made of super-hard alloy and coated with titanium nitride for scratch resistance.