PAM8403 mini type:2.3 x 1.8cm/0.9 x 0.7in,can be 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 3W (left channel)+3W (right channel) when using 4ohm load and 5V power supply. Type D power amplifier has high amplification efficiency, sound quality will not be effected by temperature rise, no need of heat sink. -in noise reduction circuit, no noise when power on/off, supports short circuit, over current and over temperature protection. Specifications: 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 a little different from the real thing. The measurement allowed error is +/- 1-3cm.