Perko 13 Vertical Fold Down All-Round Boat Navigation Light This Perko 13 Vertical Fold Down All-Round Boat Navigation Light features a black polymer base as well as a black polymer top with a clear fluted lens a frosted globe. With an adjustable angle fold-down function, it is for use on windshields, T-Tops, rails, arches and hard tops. Certified for use on power driven vessels under 20 meters 65.6 ft. in length, this boat navigation light has a reduced glare design and offers exceptional dura