... "+3"*2 4.Electroplating Knob 5.Support usb ,sd card ,vfd display Features:1. Built-in USB and SD memory card function ... , Support MP3 music format2. Nice VFD display 3. Volume, bass, treble, echo, mic-volume separately control4. Compatible with PC/VCD/DVD/CD/TUNER ... 2.1 Piano home theater system speaker ,With usb ,sd ,vfd display, fm , karaoke , mini remote function