JBL BASSPRO SL2 Self-Powered Low-Profile Underseat Vehicle Subwoofer System - 8"Make Your Drivers Seat the Best Seat In The House The BassPro SL2 self powered subwoofer fits under the front seat of many vehicles, and adds deep full rich bass to your existing audio system. Its shallow profile, 8" woofer is coupled with a custom tuned enclosure and is driven by a powerful Class D digital amplifier which making it a powerful solution. A fully variable crossover and Bass EQ are on board to tune the BassPro SL2 to your system.