USCG certified for use on power driven vessels under 20 meters (65.6 ft.) in length. 2-mile visibility. Black plastic top, chrome plated zinc alloy base 3/4″ diameter anodized tube with locking collar, and 16 degree rake. Screw size is 8. 12V bulb included. Telescoping mounting base included. Base: 3-3/4″ x 1-5/8″. Spare Base #1059T00DP.