This is a great way to add both 5v and 3.3v rails to your breadboard project.
The module accepts a standard 2.1mm center positive power adapter 9-12v DC in.
It has a 5v and 3.3v regulator on board.
You can select jumpers to place 3.3v on one rail and 5v on the other. Or have both rails the same voltage.
It has a push button on/off switch and header pins with access to the 5v, 3.3v and Ground rails.
It also has a female USB plug to power a type A cable with 5v.