2. Touch the button to switch to measure the input or output voltage, and the indicator light show which end voltage is being measured. When the machine is turned on for the first time, the digital tube displays the input voltage by default, and the input indicator IN is on; touch the button, the digital tube displays the output voltage, and the output indicator OUT is on. And it keep the last setting, even if the power is turned off and then turned on. 3. The voltmeter can be turned off by pressing the switch for more than 1 second and less than 4 seconds, and then releasing it. After the voltmeter is turned off, just press the switch shortly to turn on the voltmeter. 1. With voltmeter display, voltmeter error ±0.1V, range 5-35V. (Note: if the input voltage is lower than 4.5V, the onboard voltmeter not work and not display) 4. This module can be used in the boost field where the output voltage is higher than the input voltage, such as batteries, power , DIY adjustable voltage regulators, 24V vehicle-mounted notebook power supplies, industrial equipment step-down, 9 to 12V, 12V to 18V, 18V to 24V, etc., Weight: 0.0551155655 pounds, Manufacturer: Ehwisbe