Rockville RBS18 Single 18" 5.25 cu.ft. Vented Subwoofer Enclosure Constructed With Grade A 3/4" MDF, Made in America Using Only the Highest Quality Materials Single 18" 5.25 cu.ft. MDF Vented/Ported Subwoofer Enclosure Box Top of the line Glue for extra durable adhesion High quality GOLD spring loaded terminals Designed, tested, and engineered to work with most of todays popular woofers. These enclosures are built with the quality additives needed to maximize the performance of any sound system. Designed to give the best sound quality