USCG Certified for use on sail or power driven vessels under 20 meters (65.6 ft.) in length. 3-mile visibility. Black plastic and chrome plated zinc alloy top, black plastic base and 3/4" diameter anodized aluminum tube. 1" x 2-5/8" base. Clear lenses. 12V bulbs included. Screw size is 8. Housing Black Mount Fixed Height 5-1/16"