Space Saver - The combination of a built-in 500W amplifier that powers the 10” subwoofer makes this ideal for spatially challenged vehicles. Variable Low-Pass Filter - A low-pass filter is an electronic circuit that removes all the notes below the filter's frequency setting. You will use the low-pass filter to primarily keep high notes out of your subwoofer. Adjust it from 50-150 Hz to best fit your system. Ease of installation - Takes either speaker wire (High-level) or RCA cable (low-level) inputs. This makes connecting the QBUS10P to your radio easier since it's compatible with both factory AND aftermarket units! Automatic Turn-On - This circuit automatically turns the QBUS10P on whenever it senses an audio signal. This eliminates the need to run a remote turn on wire making installation a breeze. Variable Bass Boost - Variable Bass Boost allows you to adjust the low bass within the boost range to just the way you like it.