1: This is a QC3.0 intelligent fast charger, with voltage display, high voltage warning, it can display charging rate, there is a switch that can freely switch the mode of display and turn on/off the power.2: Press the switch lightly to turn on the power, it can display the real-time voltage after the full-screen lights up for 2 seconds, and then press the button once again to switch to the red power indicator. Both display modes can be freely switched by the button, Press and hold the switch for two seconds to turn off the power of the device. After turning off the power, it means that the device has cut off the power input and then achieve the the effect of saving electricity. 3: When the input voltage exceeds 14.6V, the red indicator light is on (warning function, it indicates that the input voltage is too high) 4: When the power is turned on and the USB charging is performed, the flowing of color screen indicates that it is in charging; it will reflect the speed of charging according to the flowing rate of color screen . When the mobile phone is fully charged, it will light up on the full screen. Two minutes later, It will display the real-time voltage again . The display mode can be switched to a separate red indicator light by pressing the switch lightly. Press and hold the switch for two seconds to turn off the power of the device. 5.Multi-purposes: supply power for cellphone, tablet PC, GPS and other USB-devices,Wide Application: cars, motorcycles, ATVs, SUVs, UTVs, Boats, etc Specifications:Product material: ABSProduct Color: Blackinput Voltage: DC 12V - 24VUSB 1 Output : DC 5V/3A;9V/2A;12V/1.5AUSB 2 Output : DC 5V/3A;9V/2A;12V/1.5ASize: 50x36.8mm Power Cable lenght: 60cm Note:1.Transition: 1cm=10mm=0.39inch2.Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid.3.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you Package includes:1 X QC 3.0 Car Dual USB Charger with LED Voltmeter ON OFF Switch1 X Power Cable with 10A fuse