Grand Seiko Quartz GMT Reference #: SBGN005
The Grand Seiko Quartz GMT (Reference SBGN005) is a 39mm stainless steel sports watch from the Sport Collection, distinguished by its "Pepsi-style" red and blue 24-hour bezel ring and high-accuracy quartz movement. It was the first Grand Seiko to feature the Caliber 9F86 GMT complication.
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Case: 39mm diameter, 12.1mm thickness, ~46mm lug-to-lug, stainless steel with Zaratsu polishing.
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Movement: Caliber 9F86 (High-Accuracy Quartz), battery-powered, ~3-year battery life (SR920SW).
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Accuracy: ±10 seconds per year (thermocompensated).
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Bezel: Fixed stainless steel bezel with a red and blue 24-hour graduated insert (day/night indication).
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Dial: Deep blue sunburst dial with applied faceted indices and broad "dauphine" hands filled with LumiBrite.
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Bracelet: Stainless steel three-link bracelet with a three-fold clasp and push-button release.
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Water Resistance: 100 meters (10 bar).
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Crystal: Dual-curved sapphire with anti-reflective coating on the inner surface.
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Functions: Hours, minutes, sweeping seconds (2 steps/sec), date at 3 o'clock, and independent jumping hour hand for GMT travel time.
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The Grand Seiko SBGN005 is powered by the Caliber 9F86, a high-accuracy thermocompensated quartz movement specifically engineered for travelers. It represents the first time a GMT complication was added to the legendary 9F series.
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Accuracy: ±10 seconds per year (at temperatures between 5°C and 35°C). The quartz crystal is aged and individually selected to ensure this stability.
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Battery Life: Approximately 3 years (uses SR920SW silver oxide battery).
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Frequency: 32,768 Hz.
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Jewels: 9 jewels.
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GMT Function: True GMT ("Caller GMT") mechanism. The local hour hand can be adjusted independently in one-hour jumps via the crown's first position without stopping the seconds or minute hands. The 24-hour hand remains fixed to "home" time.
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Date Mechanism: Instant date change at midnight, synchronized with the local hour hand.
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Seconds Hand Motion: Features the Twin Pulse Control Motor, driving the hand in two micro-steps per second to eliminate the typical quartz "tick" shudder and allow the hand to reach the edge of the dial.
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Backlash Auto-Adjust: A proprietary mechanism that eliminates gear train play, ensuring the seconds hand lands perfectly on every marker.
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Construction: Includes a protective shield construction to prevent dust from entering the movement during battery changes, extending lubricant life.
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