Weems & Plath C-1001 SOS Distress Light with Day Signal Flag USCG compliant for DAY and NIGHT use with a daytime distress signal flag (included). 33 CFR 175.130 LED light flashes up to 60 hours on C-cell batteries (3) Patented lens shines horizontal and vertical beams Visible up to 10 nautical miles Safe to operate -- NO danger to person or vessel