BOSS Audio Systems MC900B 4 Channel Amplifier for ATV UTV Car Marine - 500 High Output, Low Level Inputs, Full Range, Weatherproof, Bass for Subwoofer Power - 125 Watts Max x 4 @4 Ohms, 94 Watts RMS x 4 @4 Ohms Specs - Dimensions - 1.75? x 6.6? x 1.75?, Weighs 2.9 lbs. Bluetooth - You do not need a head unit. Just power up the MC900B and hook up some speakers to it. The included Bluetooth remote control lets you stream your music via your Bluetooth device and use apps like Spotify and Pandora Auxiliary in - The Bluetooth remote is compatible with the audio output from smartphones as well as MP3 players. Just plug in and start playing USB Charging - You can charge your USB devices using the USB charging port Weatherproof - The MC900B has been designed to handle some light weather conditions without giving up on you. It is great for use in ATVs and boats. Class AB - Class ?A? amplifiers have enormous amount of current flowing through its output transistors with no audio signal. Class ?B? amplifiers have no current flowing through its outputs with no audio signal Full Range - With a Full Range amplifier you not only have the option to run your speakers, but also your subwoofers