12V Drop-In “H” Horn with Black & White Grills. Marinco is the leading supplier of horns to the marine industry, with over fifty years of experience in designing and manufacturing sound devices specifically for use in harsh marine environments. Stainless steel is used for all critical components such as trumpets, motor cover, diaphragms, assembly and mounting hardware.. Features: 370 +/- 20Hz Fundamental Frequency. dB(A) Rating of 107 at one meter.