Marine Electric Drop in Hidden Horn W/two Grills for Boats . 12v . Five Oceans BC-2650 Grill dimensions: 67mm (H) x 125mm (W) Space required for installation: 44mm (H) x 85mm (W) x 92mm (D) (17  " x 33 " x 36 ") Loudness: 107 dB(A) at one meter. Mounting holes are 4" apart center on center