Built to withstand real-world marine duty, this M7-12IB is designed to operate without a dedicated enclosure. It boasts a monstrous 4-inch voice coil and rugged suspension system to deliver outstanding linear excursion for high output and power handling. M7-12IB is best used with amplifier power in the 200W – 600W range and is optimized to operate with a large volume of air behind it (at least 3 cu. ft. / 84.95 l). Like all JL Audio marine speakers, this driver is built to withstand a real saltwater marine environment and deliver years of listening enjoyment. The design of marine products requires extensive materials testing to achieve reliability and longevity. Building serious marine products requires a real commitment to environmental testing and materials specification. To this end, JL Audio has invested in Ultraviolet testing chambers (to simulate years of sun exposure) and Salt Fog chambers (to simulate years of exposure to salt-water environments). This testing is critical to building products that will not only sound great in your boat, but will also sound great for many, many years.