2 ports usb car charger &3.0 charger : support charging two devices simultaneously, one port is quick charge 3.0 port. this fast charge port is also compatible with: 2.0, hua wei fcp, type-c and samsung. the charger efficiency is more than 80%. Answer calls hands-free :high-performance microphone with noise suppression cvc technology, grants you crystal clear call. answering/redialing/dismissing or ending call just simply click a button. Immerse in hi-fi music: insert a usb flash driver which contains mp3 files into the rightusb port and enjoy it. if that's not enough, it can also support your playlist with no distortions of the original signal from your mp3, iphone, android smartphones and more bluetooth enabled devices. Wide compatibility :bluetooth car fm transmitter can be paired as a hands-free kit with all bluetooth enabled devices, such as iphone, ipad, ipod, tablet, samsung, htc, sony and other andriod smartphones. Multi-safety protection :comes with built-in over-current protection, over-voltage protection, intelligent temperature control, short circuit protection.