... 1.Hot 4.1 amplifier speaker 2.4.1ch circuit design 3.USB,SD,FM function 4.OEM service ... main and vice cabinets are made of MDF.2.With USB/SD card read,and FM function, remote control ... hand, high intensity, effectively eliminate resonance and cabinet noise5. With Standby,Input,Menu,VOL+,VOL- keys on the front ... 40FT1380sets 40HQ1632 sets Hot 4.1 amplifier speaker with USB/SD/FM function and VFD display