F15 Car mp3 transmit player feature: .14 channels frequency can be optical at random. . Input U disk use directly. . can input and transmit siganl from outside audio sources such as mp3/CD. . no need to change any device of car. . play by mp3, WMA format. . digital switch with one key control function. . play at the same time with unit. . Infrared remote controller. . digital tube display.