Would you like ultra-low bass that you can feel as well as hear? Then you have 2 options: 1) using conventional subwoofer & turn the volume up to the pain threshold or 2) use the " Bass Pump III" In comparison with normal speakers, the heavy " Bass-Pump III" has no membrane. Instead, it is screwed to the bottom of the vehicle. This delivers the impact sound, felt as the deepest bass, directly to the listener. So you can experience the music with the intensity of a live show, even at moderate volume. The " Bass-Pump III" is not just for in-car entertainment it can be used to give a real boost to home cinemas, Dolby Surround systems, Hi Fi systems & multimedia shows. Installation is child's play & connection is carried out no differently to a speaker or subwoofer.