USCG certified for two-mile visibility for sailboats and powerboats up to 164' (50 m). 12/24V. Direct side mount. Completely sealed design that is UV and saltwater resistant. Low power consumption. Direct replacement for Aqua Signal series 41 or series 40 with back plate PN 40901-1. Dimensions: 3.875" width x 4.25" height. x 2.375" depth. LEDs rated for 20,000 hours lifetime. An attractive and slim design that is totally maintenance free.