Recently purchased an MB102 dual power supply from Banggood.com as part of a supply+breadboard+wires combo pack. Nice little unit — provides regulated 3.3V or 5V rails from 6.5-12 V (DC) or USB power supply, and has pins set up for plugging into a standard breadboard. The two separate output rails are independently configurable for 3.3V or 5V output using jumpers.
Confirmed that the device did work as expected. Unregulated DC into the barrel socket and regulated DC out of the underside pins. The blue push-button switch turns both rails on or off (together).