"When watch is exposed natural indoor daylight or Neon light, the solar energy battery will automatically start to function. The Neon light/ light bulb should be minimum 40 Watt. When only 1 40 Watt light is used, the watch should be within 2 meters from the light source. When the light source is stronger, the watch can function at longer distances. The built-in Japanese Lithium battery works for about 5 years. About 40% of energy is saved by the Solar battery, so the life-span of the watch is increased to about 8 years. Dual Power-Solar&Lithium Battery Power Automatic Power Shift 6 digits display with backlight Chronograph with 1/100th second and lap operation Chronograph counts to 24 hours Time keeping function counts and display Hour, Minuts, Second, Month, Date Week-Day 5 Minutes Snooze Alarm and Hourly Chime00 12/24 Hours selectable" QTY/ctn: 100pcs/ctn Gross Weight: 11Kg/ctn