Premium 5.1-Channel Home Theater Speaker System (PID 10565). It features an 8" downward firing speaker driven by a 200 watt amplifier. It handles frequencies from 30Hz to 150Hz (-10dB) and uses a variable crossover from 40-150Hz. It is enclosed in a 12.6" cube and weighs about 20 lbs. The sub features four large rubber feet, which keep the downward firing driver off the floor. It includes both line and speaker level stereo inputs, so it can be used with any amplifier. A phase control switch on the back allows you to adjust the phase of the subwoofer in relation to the rest of the system .