The BK Precision 1621A220V Digital Display DC Power Supply, 18V/5A, 220VAC Line Input is a digital display power supply which uses voltage and current meters to monitor the output voltage and current. This model can be operated at constant voltage or constant current mode whose output can be varied from 0 up to the rated values for respective model. This device is compatible with other power supplies of the same model: connect two supplies in parallel to double the current output, or connect two supplies in series to double the voltage output.