The products are all tested and then divided to ensure that each component works properly to the maximum extent possible.Use process has any questions, please contact our customer service. LED working voltage 2.2V-3.4V, power module output is 3.3V,5V, please connect series buck resistor to avoid damage when using.4 digital tube display is common anode, please pay attention to the wiring rules when using?. Power module with 5.5MM * 2.5MM input interface, you can choose 9v 1A adapter as input or choose 9v battery as input (the battery needs to buy their own). Kit includes:9v1A power supply Adapter+ Breadboard Power Supply Modules+Battery Clip+830 Breadboard+DuPont wire+ IC 4N35, IC 74HC595,IC 74HC138+4-digit digital tube display+12 values Capacitor+Alligator clip+Banana Plug+10 values Resistor+5 values LED+buttons+Buzzer+Precision Potentiometer+ Thermistor+RGB LED+ Photoresistor+Pin header+Transistor+Diode etc. Minidodoca Electronics Fun Kit - The upgraded kit not only power adapter but also has more component specifications, it comes with commonly used sensors and components. Compatible with Raspberry Pi, it can meet almost all your needs.