Input reverse polarity protection.Built in output short protection function.Built in thermal shut down function.LED digital voltmeter tube, the accuracy is adjustable function, can be aimed at your multimeter adjustable accurate.Press the right key to let the display show the input or output voltage. When the right" OUT" led light, it shows output, the left "in" led show input.Type: Step-down Power Converter ModuleQuantity: 1PcInput Voltage Range: DC 2.5V - 40VOutput Voltage Range: DC 1.25V - 37VOutput Current (Max.): 3AVoltmeter Range: 0 to 40V, error +- 0.1VRed LED: Testing Input Voltage Green LED: Testing Output VoltageConversion Efficiency: 92% (Highest)Output Ripple: < 30mVSwitching Frequency: 150KHzWorking Temperature: -45 to +85 Size: 6.6cm x 3.6cm x 1.4cm/2.60" x 1.42" x 0.55" (Approx.)How to Adjust the Accuracy:Output Voltage Calibration Steps:Step 1, adjust the right button so that "OUT" LED lighted, the voltmeter shows the value of output voltage. Press the right button for more than 2 seconds, release, voltmeter and "OUT" LED flashes in synchronization so that you enter the output voltage calibration mode.Step 2, press the right button (normal speed), the voltage value is adding up a unit. Press the left button, minus a unit. Due to a unit is less than 0.1V, the minimum voltage display to 0.1V, so you need to continuously press 1-5 times to see the voltmeter change 0.1V, how many times voltmeter change 0.1V by pressing the key, depending on the current display voltage, the higher the voltage, the fewer the number of press.Step 3, press the right button for more than 2 seconds, release, to exit the output voltage calibration mode. All parameters set to automatically power down to save.Input Voltage Calibration Steps:Step 1, adjust the right button so that "IN" LED lighted, the voltmeter shows the value of input voltage. Press the right button for more than 2 seconds, release, voltmeter and "IN" LED flashes in synchronization so that you enter the input voltage calibration mode.Steps 2 and 3, consistent with the output voltage calibration method.Notes:Due to the light and screen setting difference, the items color may be slightly different from the pictures.Please allow slight dimension difference due to different manual measurement.Package Includes:1 x Step-down Power Converter Module