Sea-Dog Hidden Horn V.3 w/Grills Drop-In. 3 with GrillsDrop-In Hidden Horn V.3 with Grills is constructed of powder coated steel and injection molded nylon. Kit includes horn plus one chrome and one white decorative billet screw-in grill. Hole size 2-3/4 diameter. At 111 decibels and a frequency (Hz) of 37020A this horn meets US Coast Guard's COLREGS and ABYC standard A-23 for use on vessels under 12m (39'). 12VDC. NMMA Type Accepted #2577066. Specifications for Sea-Dog Drop-In Hidden Horn V.3 w/Grills: Manufacturer: Sea-Dog Color: Black Package Contents: Sea-Dog Drop-In Hidden Horn V.3 w/Grills Sea-Dog 431250-1: Hidden Horn V.3 w/Grills Drop-In