Grove – MOSFET enables you to control higher voltages (15VDC) with low voltage (5V) on a microcontroller. MOSFET is also a kind of switch, but its switching frequency can reach up to 5MHz, much faster than a normal mechanical relay. There are two screw terminals on the board. One for outer power source and the other for the device you want to control. Grove – MOSFET will pass the power from one end to another when closed. But if outer power source is absent, your device can still draw power from a microcontroller via the Grove interface.