This is a variable power supply also called bench power supply, made by Tenma model no 72-7660, capable of producing Variable DC Volts on its output. Variable and regulated power supplies have integrated voltage regulators for output. This translates into the regulator making sure that the output voltage will always stay at the rated value of the power supply, irrespective of the current that the device is consuming. Because of the internal regulators, output voltages do not change due to any changes in input voltage.
Each of your target devices may need a different amount of power (or DC voltage/ amperage) to function, meaning the power supply has to regulate the voltage to keep your device from overheating.
Power Supply 1x
Note: The transformer is included to make it compatible with the prevailing voltage standard.