Scan-Speak Revelator 22W/4851T00 22cm Woofer 4ohm, Rigid Paper Cone, Ferrite Magnet The Revelator woofers and subwoofers features very rigid cones in paper or aluminium that operates as a piston over a wide frequency range, in combination with Scan-Speaks low-loss linear suspension and the patented Symmetrical Drive (SD-1) it results in very low distortion and a smooth and well behaved frequency response as well as perfect transient reproduction. - Patented Symmetrical Drive Motor Design - Rigid Paper Cone - Low-Loss linear suspension - Low Damping SBR Rubber Surround - Die cast Alu Chassis vented below spider - Ferrite Magnet System w. Rubber Boot