The JBL VRX918SP Subwoofer is designed and built to the same high standards and uses the same advanced, concert-proven drivers as their VerTec series. It's a flyable speaker that delivers extraordinary power handling, clarity, flexibility and, of course, stunning JBL sound in an attractive, easy to handle and affordable package. The JBL VRX918SP will fit perfectly in medium-sized venues that don't want to sacrifice sound quality just because they're not as big as other professional facilities. For compact power, the VRX918SP subwoofer delivers.The suspendable VRX918SP subwoofer system contains a 2265G-1 neodymium magnet, patented Differential Drive, and an 18' woofer in a front-loaded, vented enclosure. It was designed specifically for use in arrays with the VRX928LA Line Array speaker and VRX-SMAF Array Frame. In addition it may also be used in arrays consisting entirely of VRX918SP subwoofers.This JBL speaker system offers complete input connection flexibility, for compatibility with a variety of cabling schemes. A recessed, external switch allows selection of either contacts +1/-1 or +2/-2 to be routed to the woofer. Equally at home in ground stacked applications, it is equipped with a top-mounted, threaded, 20 mm socket that can receive the optional SS4-BK pole. This adjustable height pole can be used to mount speakers equipped with standard 36 mm pole sockets. The threaded socket minimizes buzzing and rattling and assures that the pole will be secure and straight.The VRX918SP subwoofer's enclosure is constructed of top quality birch plywood, coated in JBL's rugged DuraFlex finish, and is heavily braced to maximize low frequency performance. The attractive CNC-machined, 16-gauge steel grille is internally lined