SB ACOUSTICS SB34NRX2-00, 34cm NOREX PAPER CONE PASSIVE RADIATORFeatures Hard paper cone for improved piston operation (made in-house) Cast aluminum chassis for optimum strength Low damping medium hardness rubber surround for improved dynamic linearity and mechanical stability Easily adjustable moving mass Specs Effective piston area, Sd 506 cm2 Free air resonance, Fs 14 Hz Compliance, Cms 0.44 mm/N Moving mass incl. air, Mms 294 g Maximum mechanical cone excursion, Xmech ±17 mm Mechanical loss, Rms 3 kg/s Mechanical Q-factor, Qms 8.62 Equivalent volume, Vas 160 liters Net weight 2.08 kg T/S parameters measured on drive units that are broken in.