The secret to Motion 40i's outstanding performance lies in its Folded Motion tweeter, 5.5-inch aluminum cone midrange driver, dual 6.5-inch aluminum cone woofers with a rear-firing bass port, and a proprietary Vojtko crossover network. This double woofer design produces vibrant, accurate deep bass performance. Motion 40i delivers the classic broad soundstage of the Motion Series from a newly designed enclosure enhanced by the slightest of modifications, including the drive-stabilizing dust cap design, stiffened motor suspension, and low-mounted woofers to reduce an acoustically harmful phenomenon known as floor bounce. The speaker's enclosure sports a reinforced baffle and a fabric grille.