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. Plastic adapters for flat or "V" type mount, contains notch for through-base wiring. Fold-down adjustable angle. Clear lenses. Height: 12-13/16". 12V bulbs included. Screw size is 8. Housing Black Mount Vertical Height 12-13/16" Base 2-1/4" x 5/8"