USCG Certified for use on power driven vessels under 20 meters (65.6 ft.).The right light for arches and towers. Thumbscrew makes for easy adjustment of light position. 360 all round navigation light in the up position, a cockpit courtesy light in the down position, or forward and out of the way for daytime skiing. Plastic adapters for flat, curved or "V" type mount, contains notch for through base wiring. 3/4" anodized aluminum pole.