Making your location known to others can have lifesaving results.Emergency Strobe flashes 50 to 70 times per minute up to 16 hours,diminishing thereafter up to 60 hours depending on battery strength and outside temperature. Strobe emits a pulsing white Xenon light visible for up to 3 miles(4.8k). Gasket-sealed lens cover makes the unit waterproof up to 15 feet. Built-in stainless steel locking pin allows for attachment to personal floatation device (PFD), backpack, pet, or clothing. Powered by one “D” cell battery (not included).