Drop-In Hidden Horn V.2 with Grills Drop-In Hidden Horn V.2 with Grills is constructed of powder coated steel and injection molded nylon. Kit includes horn plus one chrome and one white decorative billet snap-in grill. Hole size 1-7/8 x 3-3/8. At 108 decibels and a frequency (Hz) of 370 20A, this horn meets US Coast Guard's COLREGS and ABYC standard A-23 for use on vessels under 12m (39'). 12VDC. NMMA Type Accepted #2577065.WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.