JBL BassPro SL2 Compact Powered 8 Under Seat Subwoofer Enclosure (125W RMS). The 8 (200mm) woofer in the BassPro SL is designed specifically to provide low distortion, great bass performance contained in our proprietary ABS enclosure, which has a remarkably compact footprint. The amp that powers the BassPro SL produces minimal heat, and it doesn’t require a lot of current from the car’s electrical system. JBL BassPro SL2 (BASSPROSL2AM). Compact Powered 8 Subwoofer (125W RMS). Powered subwoofer with heavy-duty ABS plastic enclosure. Low-pass crossover variable from 50-120 Hz at 12 dB per octave. Variable bass boost (0 to +9 dB at 70 Hz). Phase switch (selectable 0 or 180 degrees). Speaker and line-level inputs. Frequency Response: 35-120 Hz. Dimensions: 13-9/16″W x 2-7/8″D x 10-1/16H.