The M3-650X 6.5-inch coaxial speaker is designed around the standard 6.5-inch marine speaker format with a frame design that is a direct fit replacement for most 6.5-inch marine speakers. The long excursion woofer design and excellent power handling ensures your music will play loud and clear at speed, or at anchor. Optimized for infinite-baffle operation, M3-650X woofers are designed to operate without needing an enclosure behind them.