Review on Comprehensive ELEGOO Electronics Component Pack: Arduino UNO, MEGA, Raspberry Pi Compatible with Resistors, LEDs, Switch, Potentiometer by Draek Villareal

The power supply is terrible. All plug-in power supplies like this are the same. DO NOT USE 12V AS INPUT! This will fry the power supply. It is best to use 6V. The USB outputs whatever voltage you put it on, don't connect it to something you don't want to fry. I'm not sure what its function is. These boards have many problems as I have seen from many posts on the internet. They're pretty cheap though, so you can just get more if you really want to get naughty. Although I've found many better alternatives here. The breadboard stopped working after a few hours. I don't see what's wrong with that. The components are fully functional when plugged in without a breadboard, but nothing happens anywhere I try to mount them. My multimeter says there is no continuity in some places. Jumpers are ok. It's a nice set of random components to get you started messing around with the electronics. The price is good for the components themselves. Just buy a good layout and you're solid.