SB ACOUSTICS SB34NRX-00, 34cm NOREX PAPER CONE PASSIVE RADIATORFeatures Hard paper cone for improved piston operation (made in-house) Cast aluminium 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 508 cm2 Free air resonance, Fs 8.7 Hz Compliance, Cms 0.5 mm/N Moving mass incl. air,Mms 665 g Mechanical loss, Rms 3 kg/s Mechanical Q-factor, Qms 12.1 Equivalent volume, Vas 183 liters Net weight 2.45 kg Max Mechanical Cone Excursion, Xmech ±17 mm T/S parameters measured on drive units that are broken in. Parameters apply with the pre-mounted DW50 in place.