EnrockMarine B500ABTB-3 Audio Boat ATV Car Bluetooth Marine Waterproof Amplifier with 4 Speakers (Black) Elite Series Waterproof Bluetooth Amplifier, 400 Watt 4-Channel Amp, Built-in Bluetooth for Wireless Music Streaming Works with All of Your Favorite Devices (iPhone, Android, Smartphone, iPad, Tablet, etc.) Output Power: 100 Watt x 4 MAX, Amplifier Class: AB, Bluetooth Version: 2.1, Bluetooth Wireless Range: 25' Feet, Fuse Type: 20A, Input Gain Impedance Adjustment: 1 - 300mV, Frequency Response: 15Hz - 30kHz +/-3dB Input Impedance: 10k Ohms (Low), 100 Ohm (High), Input Sensitivity: 250mV (Low), 2.5V (High), T.H.D.: &lt;0.04%, S/N Ratio: 95dB, Power Supply: DC 12V, Matching Speaker Impedance: 4-8 Ohms, Dimensions (L x W x H): 8.0" x 7.9" x 2.0" 2 Pair 200 -Watt 3.5" Inch Box Marine Waterproof Speaker System - Black