These are hard to come by for experimenting with SD (Secure Digital) cards. This board will take a single SD Card with the card connections brought out to the front of the board for easy connection. The connections are marked on the PCB. No circuit diagram is available for this device, it does however have an on board 3.3V regulator and so can be connected to a 5V supply so that the power to the SD card and interface pins are 3.3V.
As a bonous when connected to a 5V supply, 3.3V is output at the 3.3V pin.