Kanto SYD6GT Powered Speaker System 2x Optical Audio Inputs, Bluetooth Input, 3.5mm mini-jack AUX Input, RCA L/R Input Subwoofer Output, USB charge port 5V 1A 1 inch Silk Dome Tweeter, 5.25 inch Kevlar Driver Acoustic Grade MDF Cabinets, 2 inch Rear Bass Ports 4 Ohms Nominal Impedance, 87 dB Speaker Sensitivity