PM400X4The PM400X4 is perfect for 4 way front stage rear fill or 3 way front stage subwoofer systems. Simply drop a pair of component speakers on the front channels and subs on the rear and BOOM you got "The PUNCH." With its flexible design, the PM400X4 is an excellent amplifier choice for virtually any vehicle. FEATURES AT A GLANCE Features C. L. E. A. N. Set up 12dB octave Butterworth crossover On board Punch EQ with +18dB boost @ 45Hz High level input