I went to Radian site (which is extremely slow to load for me) for more complete t/s params but they are vastly different, then I noticed the one you linked is 512Be and the other is 512/2B. Not sure which to go on?
Woofer Diameter 15" / 381mm
Impedance (LF/HF) 8 ohms / 16 ohms
AES Power Rating 500 Watts
Sensitivity (1W/1m) 97dB SPL
Frequency Response 45Hz - 20kHz
Recommended Crossover 950Hz to 1.25kHz
Voice Coil Diameter(LF/HF) 4.0" / 3.0"
Nominal Dispersion 90°
Net Weight 31 lbs. / 14 kg.
Mounting Information
Overall Diameter 15.25" / 387.35mm
Bolt Circle Diameter 14.56" / 369.82mm
Baffle Cutout Diameter 14" / 355.6mm
Overall Depth 8.23" / 209.04mm
Materials
Woofer Cone Reinforced Paper
HF Diaphragm Beryllium
HF Surround Mylar
Basket Cast Aluminum
Input Connectors (HF) .25" / 6.35mm Terminals
Input Connectors (LF) Push Button Terminals
Thiele-Small Parameters
Resonant Frequency (Fs) 39 Hz
Impedance (Re) 5.9 ohms
Total Q (Qts) .313
Mechanical Q (Qms) 3.243
Electrical Factor(Qes) .346
Comp. Equivelant Vol. (Vas) 192.4 Liters
Voice Coil Overhang (Xmax) 2.85
Surface Area of Cone (Sd)m2 .089 m2