Equipped with a GMT hand, this watch features Grand Seiko’s unique Spring Drive caliber, which combines the motive force of a mainspring with the high precision. Exterior: Stainless steel Case back: Screw case back Glass Material: Dual-curved sapphire crystal Glass Coating: Anti-reflective coating on inner surface LumiBrite: Lumibrite on hands and index(es) Case size: Diameter 44.0mm Lug-to-lug 50.8mm Thickness 14.7mm Band width: 21mm Clasp type: Three-fold clasp with push button release The perimeter of Band: 191mm Movement Caliber no.: 9R66 Instructions Movement Type: Spring Drive Power reserve: Approx. 72 hours(3 days) Accuracy: ±15 seconds per month (±1 second per day) Functions Water resistance: 20 bar Magnetic resistance: 4,800 A/m Weight: 177 g Other details / Features: Rotating bezel (24-hour display) Screw-down crown 30 jewels 24-hour hand (dual time display function) Power reserve indicator Calendar-linked time difference adjustment function