Constant Current Buck Converter, DROK Numerical Control Voltage Regulator DC-DC 4.5-23V 12v to 0-20V 9v 5v 2A Step Down Transformer Module Volt Stabilized Power Supply Board with LCD Display It is DC 4.5-23.0V to 0-20.0V 0-2.00A constant current DC buck converter & digital LCD voltmeter/ammeter/watt meter. Two-way Control: DROK voltage step down converter is with both analog adjust & digital control functions. Simple wiring: IN+ for positive pole of input; IN- for negative pole of input; OUT+ for positive pole of output; OUT- for negative pole of output. LCD Display: our power supply module is designed with clear display, easy to see; allows to check preset volt, input volt, output volt, preset amp, output amp, output power and LCD brightness. Memory Function: the NC volt regulator is with preset voltage memory function and power fail preset safeguard function, it has 2-group quick volt storage, hence easy turn out needed volt/current.