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 turning off the voltmeter, just press the switch briefly to turn on the voltmeter. 1. With voltmeter display, voltmeter error ±0.1V, range 5-35V. (Note: if the input voltage is less than 4.5V, the built-in voltmeter will not work and will not display) 2. Touch the button to switch and measure the input or output voltage, and the indicator light will show which final 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 IN input indicator is on; Touch the button, the digital tube shows the output voltage, and the output indicator is on. And it will keep the last setting, even if it turns off and then power on. 4. This module can be used in the booster field where the output voltage is that the input voltage, such as batteries, power transformers, DIY adjustable voltage regulators, 24V vehicle-mounted laptop power supplies, industrial equipment reducers, from 9 to 12 V, 12 V to 18 V, 18 V to 24 V, etc., Weight: 0.0551155655 Pounds, Manufacturer: Rtxbvg