Water Resistant Bluetooth Marine 4 Channel Class A/B Amplifier Media Stereo on Boats UTV ATV Golf Carts and Cars RMS Output @ 4-Ohms: 25 watts x 4 Length: 7.8" (20 cm). Width: 4" (10 cm). Height: 2" (5 cm). USB audio input / charging: 5V/1A. Frequency Response: 20Hz - 20kHz. Conformal-coated PCB and stainless-steel hardware for weather resistance Class A/B Amplifier