The Atomic Blue Ni Glo Gear Marker glows in the dark for up to 10 hours. Battery free. Recharges by sunlight or artificial light. Uses: Be seen when walking at night and make it easier to find thinks in the dark. Attach to tent zips, backpacks, keys phones, clothing, animals or anything you may need to find in the dark. Suitable for sucba up to 25 meters or for use during night fishing. General directions: Charge Ni Glo for at least 10 minutes in direct sun or artificial light. A longer charge or stronger light increases brightness and prolongs the glow. Glows brightest in the first few hours. Recharging process possible for at least 10 years. PRC