Welcome to kacoom.th 3.7-5V Multifunction Bluetooth Receiver Audio Amplifier Board Speakers Board Description: Power supply voltage: 5V/ 3.7v Frequency response: 10-20000 (Hz) Letter ratio: 80 (dB) Output power :3W*1 Load impedance :2-3 ohms Main board functions Bluetooth (music player/speakerphone) TF/U disk (music playing) AUX (line input) FM (radio) Package Include:1*Audio Amplifier Board