12V Mini Hidden Horn. 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: Type 304 stainless steel diaphragm. Dimensions: 3.25″ W x 1.75″ H x 3″ L. Maximum amp draw: 3 Amps. dB(A)?rating: 105 at one meter. Fundamental frequency: 430 +/- 20Hz. Not designed for installation in exposed areas.