Features: 1x Auxiliary Input Screw Terminals 1x MicroSD Card Slot 4x Screw Terminals for connecting speaker cable Wired Connections: Screw Fit Speaker Terminals: Labelled; (R- & R+) for negative and positive connections to the right speaker(s), (L- & L+) for negative and positive connections to the left speaker(s). Screw Fit Auxiliary Input: For a direct wired connection to a source device such as a smartphone. Micro SD Card: The amplifier can also play MP3 tracks stored on a Micro SD Card. Simply insert card at the bottom of the panel. Technical Specification: Output Impedance: 4 to 8 Ohms Output Power RMS: 2 x 30W @ 8 Ohms (60W) Output Power MAX: 2 x 40W @ 8 Ohms (80W) Output Power RMS: 2 x 50W @ 4 Ohms (100W) Output Power MAX: 2 x 70W @ 4 Ohms (140W) Operating Voltage: 90 – 220V AC Frequency Response: 20Hz to 20 KHz Dimensions (HxWxD): 86x86x53mm Weight: 190g. Overview: Connectivity – This amplifier has a built in Bluetooth receiver allowing you to connect any devices you have with Bluetooth.