PAM8403 mini type:2.3 x 1.8cm/0.9 x 0.7in,can be easily put in small space of many digital products,high amplification efficiency It can be powered by computer USB 5V, or phone charger 5V, or lithium battery. High efficiency 90%, can provide 3W (left channel)+3W (right channel) when using 4ohm load and 5V power supply. Type D power amplifier has very high amplification efficiency, sound quality will not be effected by temperature rise, no need of heat sink. Build-in noise reduction circuit, no noise when power on/off, supports short circuit, over current and over temperature protection. : Working Voltage: 2.5V-5.5V DC (should no over 5.5V, pay attention to polarity) Suitable Speaker: 4-8ohm (4ohm is recommended); speaker power 2-8W Colour:green Material:PCB Package Contents: 5 * Power Amplifier Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.