The Seas unit U18RNX/P is a 6.5 Inch High Fidelity woofer with an injection moulded metal chassis, intended for bass reflex and transmission line designs. New Curv cone, a woven polypropylene with excellent internal damping together with perfectly matched moving parts gives a smooth, extended frequency response. Bumped back plate in the magnet system, together with the very long and light weight copper clad aluminium voice coil, allow extreme coil excursion with low distortion. Heavy copper ring below the T-shaped pole piece will reduce non linear and modulation distortion. Bullet shaped phase plug reduces compression due to temperature variations in the voice coil, avoids resonance problems which would occur in the volume between the dust cap and the pole piece and increases the long term power handling capacity. Extremely stiff and stable injection moulded metal basket, keeps the critical components in perfect alignment. Large windows in the basket both above and below the spider reduce sound reflection, air flow noise and cavity resonance to a minimum.