Jim Buoy 9000-X LED Lights for navigational aid, marker and jack lighting provide long lasting battery operation with a waterproof construction to survive saltwater corrosion and the most severe weather conditions. 9000-X flashes 30 times per minute and lasts up to one year without a battery change Polycarbonate fresnel lens for up to 1 mile visibility Impervious to water plastic construction Electronic shut off during day and on at darkness Run on 3 Alkaline D-Cell batteries (not included) HOW IT WORKS - On navigation buoys, the bottom of the 9000-X light is glued onto a flange (sold separately) which is screwed down onto the top of the buoy. The top portion of the 9000-X light is then screwed onto the bottom portion of the light. This allows 4" of the light to appear above the buoy and the remaining 7" being internal to the buoy. All 9000-X functions are electronically controlled, remaining OFF during daylight and automatically turning ON at night. The 9000-X issues a bright, pulsating light (30 flashes per minute) that is visible for up to 1 mile and will last up to one year without a battery change. The great longevity, convenient size and low cost of the 9000-X make it possible to place lights in many areas that in might have been impractical.