Product Name: bluetooth Receiver Amplifier Board Material: Electronic Components Color: White Size: 4x2.4cm(L x W) Mounting Hole:3.0mm Audio Input: bluetooth Audio Receiver Amplifier Output Power: 2x3W (Output connect to speakers, can not output for amplifier) Driving speaker impedance: 4~8ohm Power Supply Interface: Micro USB (Connect to computer USB port or battery bank USB, both can supply 5V) Output Interface: 2.54 Pitch, 4 Pins