The lightweight, front-loaded, vented ASB7128 High Power Dual 18" Subwoofer housing two of JBL's exclusive 2269H Ultra Long Excursion 18" Differential Drive woofers., features neodymium magnet, dual voice coils and dual gaps, JBLs exclusive Vented Gap Cooling and ultra robust composite cone for high excursion and extra long life. The woofer is capable of a peak-to-peak maximum excursion of 3.5". You will also enjoy Parallel/Discrete switchable input modes.