3.1 speaker system with AC/DC input all functions handle by remote control USB/SD Reader,FM player,kara **3.1 speaker ... front panel front panel control for volume,treble,bass,balance.with USB/SD interfacewith Digital FM TuningAll functions handle by remote controlOutput ... ::≥75dB±3dBTHD:≤1%G.W:7.6KG0 3.1 speaker with USB/SD