The R1 650.4 marine-grade amplifier, made by Roswell, is everything your boats audio system has always wanted. These stackable amplifiers utilize a 4-channel Class-D design, that puts out 100 watts RMS per channel at 4, and are perfect for powering your R1 6.5" marine speaker setup. Easily bridge & tune with the calibrated crossover controls. Because LEDs create lots of noise issues, this amp features differential RCA inputs for maximum noise rejection. The R1 650.4 is built with fully conformal-coated PCB&&';;s and nickel-plated marine-grade wire terminals to ensure their quality. Each sold separately Continuous Power (RMS) 4: 100W x 4 2: 165W x 4Bridged 4: 300W x 2Frequency Response 10-25 kHzInput Sensitivity 0.2 - 10.0VHPF (High Pass Filter) 30Hz - 300HzLPF (Low Pass Filter) 30Hz - 300HzBass EQ 0 ~18dB @ 45HzDimensions Inches: 1.90 x 7.0625 x 11.125 Centimeters: 4.83 x 17.94 x 28.26