The MB102 is a compact power supply module that plugs directly into standard 830 or 400 hole breadboards, providing both 3.3V and 5V constant output simultaneously. It can be powered from USB or a 6.5V-12V DC adapter; 3.3V or 5V can be independently selected for each rail via jumpers on the module. Thanks to the ON/OFF switch, power can be cut without disturbing the circuit connections. Unlike feeding the breadboard from the 5V pin of Arduino and ESP series boards, it provides a separate power supply, limiting the current to the board and making the circuit safer.