With a voltage meter and voltmeter displays self-calibration. Uses a more advanced microprocessor voltage voltmeter error ± 0.05V, Range 0 - 40V. (To ensure accuracy voltmeter, make sure the input voltage of 4.5V and above). Touch of a button to switch the input or output voltage measurements and has a light show which is being measured voltages, and save the settings, even the power off and then on. The voltmeter can be turned off when not needed, easily with the touch of a button on the left. With terminal blocks, it can be used easily without a soldering iron, and the soldering wire connection points are retained. Input Voltage 4.5- 40V. (Input voltage must be higher than the output voltage of 1.5v or more) Adjustable output voltage range of 1.25V - 37V continuously adjustable. (Input voltage must be higher than the output voltage of 1.5V) Output current 3A, recommendations within 2.0A use, high current needed to enhance heat dissipation. Output power 20W, 15W, please enhance heat dissipation over. High conversion efficiency, on average 88% (efficiency and the input and output voltage, current, pressure related). With reverse polarity protection, reverse polarity does not burn. With overheating protection and short circuit protection function. Application: This module can be applied to fields in the input voltage is higher than the step-down output voltage, such as batteries, power transformers, DIY adjustable power supply, 24V Car T of the power equipment industry buck, 12V switch 3.3V, 12V switch 5V, 24V switch 5V, 24V switch 12V, 36V 24V turn and so on. Colour:Blue Material:PCB+electronic components Size:66mmx36mm Package Contents: 3 * DC DC Step Down Converter