The drop-in V.1 hidden horn is constructed of powder coated steel and injection molded nylon. At 106 decibels and a frequency (Hz) of 440±20A this horn meets ABYC standard A-23. Kit includes horn plus one each chrome and white decorative billet snap-in grills. For use on vessels under 39'. 12VDC. Required hole size, 1-7/8" x 3-3/8".