Great for use as a flashing light where it is suitable for marking a location Internal light sensor turns it on in dark, off in daylight To manually turn off in dark condition -- Partially unscrew the lens or remove the batteries O-ring seal and the body of the light is a sealed single plastic housing Water-resistant, ideal for buoy attachment, not for prolonged submersion Long Battery Life: Over 200 hours, efficient circuitry powered by 2 AA batteries Standout Flash Pattern: Features a unique flashing pattern of TWO flashes per second amplified by an advanced Fresnel lens for enhanced recognition Visibility at night is close to 3/4 mile depending on conditions affecting visibility Somes colors are restricted. Please check with local authorities. Blinky Lights Marine Fishing Strobe, Blue LED Flashing, Pack of 5, Model SP, Glow Stick Replacement