Description: The circuit board is made of FR4-A high quality PCB, and it is tinned and beautiful. Power supply: DC005 and the 2P pin next to it are the power supply interface. Voltage: 3-12V Audio input: The 3.5MM audio dock on the board and the pin next to it are audio input ports, which can be selected according to personal convenience. Speaker: 2P pin is the speaker interface, the speaker is non-polar component, so the speaker will not burn out if you pick it up. Specification: Material: electronic components PCB board size : approx. 37 x 35mm/ 1.46 x 1.38inch Package Includes: A set of materials 1 Piece PCB 1 Piece 100K adjustable resistance 1 Piece Potentiometer knob housing 6 Pieces Pin header 2 Pieces 4.7K resistor 1 Piece 10 ohm resistor 1 2 Pieces 104 ceramic capacitor 2 1 Piece DIP8 IC socket 1 Piece LM386 1 Piece DC005 seat 1 Piece 3MM LED 1 Piece 10UF capacitor 1 Piece 100UF capacitor 1 Piece 1000UF capacitor 1 Piece 3.5 audio seat (4 Pack) Note: Please allow 1-3mm error due to manual measurement. Please make sure you do not mind before you bid. Photo color might be a little different from the actual product due to color display of different monitors. Thanks for your understanding and enjoy your shopping moment.