The UST See-Me 2.0 Strobe personal locator light strobes 60 times per minute providing 45 lumens of light for maximum visibility in all directions. This U.S. Coast Guard approved LED strobe automatically activates when it comes in contact with water.FeaturesLifetime LED bulb never needs to be replacedProvides 45 lumens of light; runs for 120 continuous hoursWaterproof IPX7Activates when submerged in water; will not automatically activate with rain, sea spray, or high humidityCan be manually activated with easy twist On/OffExcellent personal locator light when attached to gear or pack on the trailVisible 3.1 miles (5.0 km) on a dark, clear night exceeding USCG requirements of 1 nautical mile (1.9 km) visibilityClip, lanyard cord, and hook-and-loop strap includedBATTERIES: 2 x AA alkaline batteries (not included)