ES-PRO 90.4High end 4CH fulrange Mini class D amplifierPCB Layers:Double LayersInput Sensitivity:0.2-5VX-OVERRANGE(LPF):80HZX-OVERRANGE(HPF):80HZMini Size easy for installing4Ohm stable in sterio modeTotal Harmonic distortion:0.5%Military grade PCBDirect Short,Thermal&Overload Circuit Protection..