DROK Mini 5V Digital Audio Amplifier Board USB Powered 2-Channel Stereo Amp DIY 3W+3W 470uf PAM8403 Mini Power Amplifier Board. Operating voltage: DC 2.5-5 .5 V Max output: 3Wx2 Power supply filtering: 470uf Dimension:29.5 x 20.2 x 15mm (excluding protruding potentiometer handle)