This breadboard 3.3V / 5V power supply module fits the power rails on most breadboards. It also features a mini USB power port to supply power to external devices.
Specifications:

1. input voltage: 7-12 VDC or USB 5 V power supply (use regulated supply)
2. output voltage: 5 VDC fixed + 3.3 V / 5 V, switchable
3. maximum output current: maximum 500 mA, onboard 500 mA resettable fuse
4. two power rails: 1 rail fixed 5 V the other selectable 3.3 V or 5 V
5. DC input: 5.5 x 2.1 mm plug

vma424_a4v01.pdf

ce_rohs_open.pdf