Kicker 08ZX3504 4X90-Watt 4-Channel Amplifier 4 x 90 Watt stereo amplifier Built-in 12dB/octave high-, low-, or all-pass electronic crossover variable from 50 to 200 hertz KICKEQ Boost offers up to 18 decibels of bass centered at 40 Hz Balanced differential inputs for noise elimination One-year limited warranty