Replacement QSC 18" 1000-Watt 8 Ohms Sub Woofer Speaker For QSC HPR181 Series 647356208416 | eBay
QSC Gp218-Sw-Bk Dual 18" Subwoofer; Same Acoustical Performance As The Wl218-Sw, Rectangular Enclosure With 16 X M10Suspension Points; Available In Black - Technostore
QSC KS118 3600W 18 inch Powered Subwoofer | Sweetwater