Description: Dual USB3.1A fast charging battery voltage detection. Support music / TF card / U disk playback, support hands-free calling. LED screen for displaying frequency, song number and working status information. Support folder switching playback function, song classification and playback. Support power-off memory function. 2 mobile phones are charged at the same time, support while listening to songs and charging. Noise cancellation function, built-in noise cancellation circuit, making the call sound clearer. Specification: Support expansion: U disk / TF card S32G (Not Include) Power supply: DC 5V Output current: 3.1A Transmission frequency: 87.5MHz - 108.0MHz Protection: short circuit / over voltage / over current / over power / under voltage / over temperature protection Product size: 86x51.5x45.5mm Package Includes: 1 x Car Handfree FM Transmitter 1 x User Manual Note: Transition: 1cm=10mm=0.39inch Please allow slightly 0-1cm difference due to manual measurement. Colors can appear different depending on light and how the listing is viewed. Thanks for your understanding and attention. Wish you a pleasant shopping experience!