Impressively built, high efficiency, 15" drivers. Click JBL Pro website for details, including T/S params. I have three with brand-new JBL factory recone. One is serving duty as my front sub: In that 4 cu ft vented, sixth-order alignment (which is identical to JBLs venerable B380 sub) response is -3dB @ 24Hz. If anyone's interested in a turn-key sub, I suppose I could sell this one with equalizer for ~$400, but shipping would be expensive (buyer pays). The other two are still in shipping cartons from JBL. While they make great subs, they also have very smooth response to well above 800Hz and can be used as woofers as well. Indeed, JBL used these drivers in many of their high-end home and studio monitor systems Current list is $340 ea. I will sell these for $190 ea.