Hazard 4 Heavy Water Diver BlackTie B Yellow GMT Unisex Analog Watch 50mm Silver Nylon. ) Tritium bulbs don't charge by battery sun or flashlight unlike other watches using simple luminescent paint or battery-run film. They don't fade overnight like those paints and require no button pushing or battery to exhaust. They are also feather-light. Tritium lights are usually used only for critical applications like military compasses and night-sights; we nevertheless source them since our watches are used by those for whom timing can determine survival/success or catastrophe. Specifications for Hazard 4 Heavy Water Diver BlackTie B GMT Unisex Analog Watch: Manufacturer: Hazard 4 Size: One Size Application: Around Town Work Tactical Duty Gender: Unisex Dial Color: Black Illumination Color: Green Amber/Gold Yellow Band/Strap Color: Black Case Color: Silver Marker/Numeral Color: White Case Finish: Matte Case Material: Titanium Case Diameter: 50 mm Bezel Finish: Silver Band/Strap Material: Nylon Wrist Band Type: Strap Movement: Quartz Illumination Type: Tritium Weight: 3.8 oz Condition: New Style: Original Casual Performance Age Group: Adults Seasonal/Temperature Use: All Seasons Quantity: 1 Package Contents: Hazard 4 Heavy Water Diver BlackTie B GMT Unisex Analog Watch Hazard 4 HWD-TI-G-Y-KW-GGYG: Heavy Water Diver BlackTie B Yellow GMT Unisex Analog Watch 50mm Silver Nylon