M-Series 7.7-inch Marine Cockpit Coaxial System for Infinite-Baffle Use (100 W, 4 Ω) - White Sport Grille. Purpose-engineered and built for real marine duty, M-Series coaxial systems deliver maximum audio performance in any open-air boating environment. The oversized 7.7-inch design of the M770-CCX coaxial results in increased efficiency (more output for a given amount of power). Combine that advantage with long excursion and excellent power handling and you have a speaker system truly capable of playing loud and clear in a powerboat at speed. The woofer element is optimized to operate with a large volume of air behind it (at least 2 cu. ft. / 57 l).