Also you can play music from Micro USB or Micro SD card. This unit is widely used for room for home, office, hotel, etc. It’s recommended to connect with 2 speakers. Stereo Amplifier Module (2 x 15W) connect up to 2 speakers. BT connectivity for wireless audio input of pad, smartphones, etc. 1 x Wired Audio Input (on rear PCB). Micro USB and TF card player (at bottom of unit). Screw terminations on the rear of the unit for loudspeakers, power and wired line input. Includes in-line power supply. Power Supply: AC100-240V, 50-60Hz. Output Impedance: 4? Or 8? Extended Micro SD card up to 32G. BT Transmission Distance:? 15M. Product Size: 86 x 86 x 44mm. 1 x mounting frame. 2 x screws for mounting. 1 x back box. 1 x Micro USB to USB connector.