This dual QC3.0 USB ports car charger can simultaneously charge two devices that support the QC3.0 protocol at QC3.0 speed. The fast car charger total power 36W, maximum output of each port up to 18W. Some mobile devices do not support QC3.0, this USB car charger fast charge at maximum charging speed your device supports. This fast car charger with colorful voltmeter & ON/OFF switch. When dual QC3.0 port not connected to mobile devices, the colorful voltmeter will always display the voltage value of the car battery in real time. When the car charger USB port connect to devices, the colorful LED lights flash and rotate, and the speed of rotation reflects the charging rate. At this time, the colorful voltmeter does not display the voltage value. Touch ON/OFF switch lightly, LED light will stop flashing and turning. At this time, the red indicator light is on, and dual QC3.0 ports still charge mobile devices. Long press the switch about two seconds, both colorful voltmeter & QC3.0 port power turn off, car charger in non-working state. You can lightly touch the switch again to switch the car charger back to working state. This universal cigarette lighter USB charger is made of high temperature and low temperature resistant materials, can be used in -20 to 60( ) working environment. Built-in intelligent control chip and 10A fuse: provide overcurrent protection, overvoltage protection, overtemperature protection, overcharge protection, short circuit protection, reverse wiring protection. Ensure the safety of your charging device and vehicle battery. Quickly identify charging devices in one second. This universal cigarette lighter USB car chgarger provides the fastest possible charging for all non-fast charging devices. You can freely switch colorful voltmeter display mode and turn power on & off through the ON/OFF switch. Built-in high-quality spring, easy to plug & unplug. Compact body design, perfect fit with most car cigarette lighter socket.