Hifonics TPS-A350.4 350W Class-D 4-Channel Powersports Amplifier Waterproof Hifonics TPS-A350.4 THOR Series 350W Class-D 4-Channel Powersports Amplifier  Hifonics TPS-A350.4  Class-D Full Range 2-Ohm Stable 4-Channel Powersports Amplifier  Peak Power Rating:  4 ohms: 40 watts x 4 chan.  2 ohms: 80 watts x 4 chan.  Total power output: 350 watts  Tested to withstand water, , mud and vibration  Pulse Width Modulated MOSFET power supply  4 channel operation  3-way  circuitry (thermal, overload, and speaker short )  Heavy duty aluminum alloy heat-sink  Frequency Response: 20 - 20,000 Hz  Signal to Noise Ration: > 90 dB  Variable Bass Boost: 0 to +12 dB bass boost  Fuse Rating: 30 A x 1  Dimensions: 3.7"W x 5.5"L x 1.77"H  Authorized Internet Dealer  1-year Manufacturers Warranty