With the Ellipticor family a long tradition of circular motor structures and their inherent breakup behavior has been broken since one of its key features is an elliptical voice coil and magnet gap. In combination with the powerful SD AirCirc magnet system the 21WE has high sensitivity, very low distortion, and has an extremely fast response to transients. Above all a TRUE TO LIVE sound which makes 21WE/8542T00 one of the very best midwoofers on the market!