1. with voltmeter display, the voltmeter error is 0.1V, and the range is 5~35V. (Note: if the input voltage is lower than 4.5V, the onboard voltmeter will not work and will not display) 2. touch the button to switch to measure the input or output voltage, and there is an indicator light to 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 keeps 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. 4. with terminal blocks, it is easy to use without a soldering iron, and the connection points are reserved(The input voltage must be more than 1v higher than the output voltage) 5. The maximum output current can be up to 3A, and the recommended working current is about 2A. If it exceeds 2A, add a heat sink 6. It uses an internal oscillation frequency of 400KHz, which belongs to the second generation of switching voltage regulators, with low power consumption and high efficiency. 7. 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. Input range: 4.5V~32V Output range: 5V~35V(adjustable) Input current: 4A (Max) Note: Batch different, silkscreen/appearance differences, does not affect the use Colour:Blue Material:PCB+Electronic Components Package Contents: 2 x XL6009 DC-DC Booster module Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.